Corneal topography measurement and alignment of corneal surgical procedures

ABSTRACT

Methods and apparatus are configures to measure an eye without contacting the eye with a patient interface, and these measurements are used to determine alignment and placement of the incisions when the patient interface contacts the eye. The pre-contact locations of one or more structures of the eye can be used to determine corresponding post-contact locations of the one or more optical structures of the eye when the patient interface has contacted the eye, such that the laser incisions are placed at locations that promote normal vision of the eye. The incisions are positioned in relation to the pre-contact optical structures of the eye, such as an astigmatic treatment axis, nodal points of the eye, and visual axis of the eye.

CROSS-REFERENCE

This application claims priority to U.S. provisional application No.61/813,613, filed on Apr. 18, 2013, entitled “CORNEAL TOPOGRAPHYMEASUREMENT AND ALIGNMENT OF CORNEAL SURGICAL PROCEDURES,” and U.S.provisional application No. 61/873,071, filed on Sep. 3, 2013, entitled“CORNEAL TOPOGRAPHY MEASUREMENT AND ALIGNMENT OF REFRACTIVE SURGICALPROCEDURES,” the entire contents of which are incorporated herein byreference.

The subject matter of the present disclosure is related to the followingpatent applications: U.S. application Ser. No. 12/048,182, filed 3 Mar.2008, entitled “METHOD AND APPARATUS FOR CREATING INCISIONS TO IMPROVEINTRAOCULAR LENS PLACEMENT”; U.S. application Ser. No. 12/048,186, filed13 Mar. 2008, entitled “METHOD AND APPARATUS FOR CREATING OCULARSURGICAL AND RELAXING INCISIONS”; U.S. App. Ser. No. 61/722,064, filed 2Nov. 2012, entitled “LASER EYE SURGERY SYSTEM CALIBRATION”; U.S. App.Ser. No. 61/813,613, filed Apr. 18, 2013, entitled “CORNEAL TOPOGRAPHYMEASUREMENT AND ALIGNMENT OF CORNEAL SURGICAL PROCEDURES”; U.S. Pat.App. Ser. No. 61/788,201, filed Mar. 15, 2013, entitled “MICROFEMTOTOMYMETHODS AND SYSTEMS” ; U.S. Ser. No. 61/813,172, filed Apr. 17, 2013,entitled “LASER FIDUCIALS FOR ALIGNMENT IN CATARACT SURGERY,”; theentire disclosures of which are incorporated herein by reference andsuitable for combination in accordance with embodiments disclosedherein.

BACKGROUND

The present disclosure relates generally to photodisruption induced by apulsed laser beam and the location of the photodisruption so as to treata material, such as a tissue of an eye. Although specific reference ismade to cutting tissue for surgery such as eye surgery, embodiments asdescribed herein can be used in many ways with many materials to treatone or more of many materials, such as cutting of optically transparentmaterials.

Cutting of materials can be done mechanically with chisels, knives,scalpels and other tools such as surgical tools. However, prior methodsand apparatus of cutting can be less than desirable and provide lessthan ideal results in at least some instances. For example, at leastsome prior methods and apparatus for cutting materials such as tissuemay provide a somewhat rougher surface than would be ideal. Pulsedlasers can be used to cut one or more of many materials and have beenused for laser surgery to cut tissue.

Examples of surgically tissue cutting include cutting the cornea andcrystalline lens of the eye. The lens of the eye can be cut to correct adefect of the lens, for example to remove a cataract, and the tissues ofthe eye can be cut to access the lens. For example the cornea can be toaccess the cataractous lens. The cornea can be cut in order to correct arefractive error of the eye, for example with laser assisted in situkeratomileusis (hereinafter “LASIK”) or photorefractive keratectomy(hereinafter “PRK”), for example.

Many patients may have visual errors associated with the refractiveproperties of the eye such as nearsightedness, farsightedness andastigmatism. Astigmatism may occur when the corneal curvature is unequalin two or more directions. Nearsightedness can occur when light focusesbefore the retina, and farsightedness can occur with light refracted toa focus behind the retina. There are numerous prior surgical approachesfor reshaping the cornea, including laser assisted in situkeratomileusis (hereinafter “LASIK”), all laser LASIK, femto LASIK,corneaplasty, astigmatic keratotomy, corneal relaxing incision(hereinafter “CRI”), Limbal Relaxing Incision (hereinafter “LRI”),photorefractive keratectomy (hereinafter “PRK”) and Small Incision LensExtraction (hereinafter “SMILE”). Astigmatic Keratotomy, CornealRelaxing Incision (CRI), and Limbal Relaxing Incision (LRI), cornealincisions are made in a well-defined manner and depth to allow thecornea to change shape to become more spherical.

Cataract extraction is a frequently performed surgical procedure. Acataract is formed by opacification of the crystalline lens of the eye.The cataract scatters light passing through the lens and may perceptiblydegrade vision. A cataract can vary in degree from slight to completeopacity. Early in the development of an age-related cataract the powerof the lens may increase, causing near-sightedness (myopia). Gradualyellowing and opacification of the lens may reduce the perception ofblue colors as those shorter wavelengths are more strongly absorbed andscattered within the cataractous crystalline lens. Cataract formationmay often progresses slowly resulting in progressive vision loss.

A cataract treatment may involve replacing the opaque crystalline lenswith an artificial intraocular lens (IOL), and an estimated 15 millioncataract surgeries per year are performed worldwide. Cataract surgerycan be performed using a technique termed phacoemulsification in whichan ultrasonic tip with associated irrigation and aspiration ports isused to sculpt the relatively hard nucleus of the lens to facilitateremoval through an opening made in the anterior lens capsule. Thenucleus of the lens is contained within an outer membrane of the lensthat is referred to as the lens capsule. Access to the lens nucleus canbe provided by performing an anterior capsulotomy in which a small roundhole can be formed in the anterior side of the lens capsule. Access tothe lens nucleus can also be provided by performing a manual continuouscurvilinear capsulorhexis (CCC) procedure. After removal of the lensnucleus, a synthetic foldable intraocular lens (IOL) can be insertedinto the remaining lens capsule of the eye.

Prior short pulse laser systems have been used to cut tissue, and havebeen used to treat many patients. However, the prior short pulse systemsmay provide less than ideal results in at least some instances. Forexample, the alignment of the eye with the laser surgery system can beless than ideal in at least some instances, such as when refractivetreatment of the cornea of the eye is combined with a treatment of thelens of the eye such as removal of the cortex and nucleus from the eye.

The eye comprises complex optical structures, and at least some of theprior laser eye surgery systems can be less than ideally suited to treatat least some eyes. For example, it could be helpful to decrease higherorder aberrations of the eye such as spherical aberration and coma, andat least some of the prior methods and apparatus of treating the eye canbe less than ideally suited for correcting aberrations of the eye. Forexample, misalignment of the eye with the surgical treatment apparatuscan result in less than ideal placement of incisions in at least someinstances.

Although prior systems have attempted to combine laser eye surgerysystems with data from eye measurement devices, the results can be lessthan ideal in at least some instances. The surgical eye can be alteredas compared with the natural eye, and anatomical structures of thesurgical eye may not coincide with anatomical structures of the eyeprior to surgery. For example, the cornea can be distorted duringsurgery, for example from contact with the patient interface or fromalternation of the surface of the cornea. Also, the eye can undergocyclotorsion when moved from one measurement system to anothermeasurement system such that alignment of the angle of the eye can beless than ideal. Also, the pupil of the eye during surgery can differfrom the pupil of the eye that would be used for normal vision, whichcan make alignment of the eye with surgical incisions and intraocularlenses more challenging than would be ideal. For example, in at leastsome instances the pupil of the eye can dilate and affect the locationof the center of the pupil.

There are other factors that may limit the usefulness of data providedto a surgical laser from eye measurement devices such as tomography andtopography systems. For example, there can be at least some distortionof at least some of the images taken among different devices, and thisdistortion can make the placement of laser incisions less than ideal inat least some instances. Also, the use of different systems formeasurement and treatment can introduce alignment errors, may take moretime that would be ideal, and may increase the cost of surgery such thatfewer patients than would be ideal can receive beneficial treatments.

At least some prior ophthalmic laser surgery systems can be less thanideally suited for combination with prior topography systems. Forexample, prior laser surgery systems for cutting the cornea may rely ona patient interface that can make measurements of the cornea less thanideal in at least some instances. The prior patient interfaces may applyforce to the eye, for example with a suction ring that engages the eyenear the limbus. The resulting force can distort the corneal shape anddecrease accuracy of the corneal measurements in at least someinstances. The distortions of the cornea related to placement of thepatient interface can limit the accuracy of corneal measurements andalignment of the corneal surgical procedures. Also, the images obtainedwith prior laser systems configured to couple to the eye with patientinterfaces can be distorted at least partially in at least someinstances, which can make combination of the images from prior lasersurgery system with prior eye measurement systems such as cornealtopography and tomography systems less than ideal in at least someinstances.

In light of the above, it would be desirable to provide improved methodsand apparatus that overcome at least some of the above limitations ofthe above prior systems and methods. Ideally, these improved systems andmethods will provide improved alignment with the eye during surgery,improved placement of laser beam pulses to incise the eye, improvedplacement of refractive incisions of the eye, improve placement ofincisions for intraocular lenses, corneal topography from the lasersurgery system without distorting the corneal shape, and integration ofthe measurement data with the laser treatment parameters, in order toprovide an improved result for the patient.

SUMMARY

Embodiments as described herein provide improved treatment of materialssuch tissue. In many embodiments the tissue comprise ocular tissue suchas one or more of corneal tissues or lenticular tissue incised, forrefractive surgery such as the placement of intraocular lenses orcorneal incisions and combinations thereof. In many embodiments,improved methods and apparatus for performing laser eye surgery areprovided for beneficially placing laser incisions on tissue structuresof the eye when the eye comprises distortions related to the laser eyesurgery, such as distortion related to coupling the eye to an interfaceof the laser system or distortions related to substances applied to theeye during surgery. The embodiments as described can also be used toalign the incisions with locations of the eye that may not be readilymeasured when the patient interface contacts the eye and inhibitsmovement of the eye, such as optical structures defined when the patientviews a target and the eye moves freely and optical structures definedwithout distortion of the eye. Many of the embodiments as disclosedherein are also well suited for combination with laser eye surgerysystems that do not rely on patient interfaces, such as laser surgicalsystems used in combination with pharmacological substances that mayaffect vision of the eye. The embodiments as described herein canprovide improved placement of intraocular lenses in relation totreatment axes and the nodal points of the eye, such that the placedlens can provide a post surgical eye having similar nodal points to thepre-operative eye in order to provide improved accuracy of correctionand decreased aberrations with the replacement lens. In manyembodiments, intraocular lenses are identified for treatment in responseto locations of the measured nodal points of the eye in order to providesimilar locations of the nodal points of the post-operative eye.

In many embodiments, the eye is initially measured without contactingthe eye with a patient interface, and these measurements are used todetermine alignment of the incisions when the patient interface contactsthe eye or when the eye has been distorted with a pharmacologicalsubstance, and combinations thereof. The eye of the patient can bemeasured when the patient has been placed on a patient support of thesurgical laser prior to the patient interface contacting the eye, andthese measurements can be used to determine locations of the laserincisions when the patient interface contacts the eye. Alternatively orin combination, one or more tissue structures of the eye can be measuredaway from the patient support of the surgical laser and prior tocontacting the eye with the patient interface, and these measurementsused to determine locations of one or more optical structures of the eyewhen the patient interface contacts the eye. The pre-contact locationsof the one or more structures of the eye can be used to determinecorresponding post-contact locations of the one or more opticalstructures of the eye when the patient interface has contacted the eye,such that the laser incisions are placed at locations that promotenormal vision of the eye. This approach has the advantage of positioningthe incisions in relation to the pre-contact optical structures of theeye, even when the eye has been distorted as may occur with the patientinterface or with substances placed on the eye during surgery such asmydriatic substances.

While the locations of the incisions on the eye can be determined in oneor more of many ways, in many embodiments an image of the eye coupled tothe patient interface is displayed to a user with one or moreidentifiable markings provided on the display to show the user thelocations of the one or more optical structures of the eye. Thelocations of the one or more optical structures of the eye can bedetermined from the measurements obtained prior to contacting the eyewith the interface and positioned on the image of the eye coupled to theinterface in order to reference the incisions of the eye in relation tothe locations of the one or more optical structures prior to the patientinterface contacting the eye. The image of the eye may comprise asagittal view of the eye, a transverse view of the eye, or an anteriorview of the eye, and combinations thereof. The one or more images of theeye may comprise a tomography image showing a plane of the eye and ananterior camera view of the eye, and the one or more optical structurescan be placed on the one or more images to provide one or more referencelocations to the user. In many embodiments, the one or more imagescomprise real time images provided for the user to plan and evaluate theprogress of the incisions placed on the eye. Providing the tomographyimage and the anterior image with markers can be particularly helpfulfor the user to identify one or more axes of the eye related to visionwhen the interface contacts the eye, such as when the one or more axesof the eye extend away from an axis of the optical delivery systemthrough one or more apparent layers of the eye, such as from an entrancepupil of the eye adjacent the lens to the front surface of the cornea.

The optical structure of the eye may comprise one or more structures ofthe eye related to optics of the eye, and the tissue structure of theeye may comprise one or more tissues of the eye. The optical structureof the eye may comprise one or more of an optical axis of the eye, avisual axis of the eye, a line of sight of the eye, a pupillary axis ofthe eye, a fixation axis of the eye, a vertex of the cornea, an anteriornodal point of the eye, a posterior nodal point of the eye, an anteriorprincipal point of the eye, a posterior principal point of the eye, akeratometry axis, a center of curvature of the anterior corneal surface,a center of curvature of the posterior corneal surface, a center ofcurvature of the anterior lens capsule, a center of curvature of theposterior lens capsule, a center of the pupil, a center of the iris, acenter of the entrance pupil, or a center of the exit pupil of the eye.The optical structure of the eye may comprise a pre-contact opticalstructure determined with measurements obtained prior to the interfacecontacting the eye, or a post-contact optical structure of the eyedetermined with measurements obtained when the interface has contactedthe eye. In many embodiments, the optical structure comprises thepre-contact optical structure and the location of the pre-contactstructure is determined on the post-contact eye in relation to one ormore post-contact tissue structures of the eye. The one or morepost-contact tissue structures may comprise one or more of the iris, aplane of the iris, an outer boundary of the iris, the limbus, a centerof the limbus, sclera blood vessels, a center of the cornea, a thicknessprofile of the cornea, a center of curvature of a thickness profile ofthe cornea, a tissue stained with a dye such as an ink, the vertex ofthe cornea, the optical axis of the eye, a center of curvature of theanterior surface of the cornea, a center of curvature of the anteriorlens capsule, a center of curvature of the posterior lens capsule

In many embodiments, an axis of the optical delivery system is shown onthe display and the one or more images of the eye with an identifiablemark on the display such, such as a reticle to indicate the location ofthe axis of the optical delivery system.

In many embodiments, the laser eye surgery system comprises a fixationlight viewed by the patient when a ring of the patient interface isplaced on the eye in order to improve alignment of the patient interfacewith the eye. The fixation light may be adjustable to the patient inorder to decrease blur when the patient views the light prior toplacement of the patient interface on the eye and also when patientinterface contacts the eye and decreases optical power of the eye. Whenthe patient interface has been placed on the eye, the patient may beasked to look at the light or describe the location of the light inorder to confirm alignment of the patient interface with the eye.Alternatively or in combination, the reflection light from the corneamay be displayed with the real time anterior image of the eye, which canassist the user with alignment of the eye. In many embodiments, the oneor more marks indicating the locations of one or more optical structuresof eye can be shown on the display with the reflection of the fixationlight in order for the user to determine alignment of the eye. The oneor more marks may identify locations of one or more optical structuresof the eye prior to contact with the patient interface, or identifylocations of one or more structures of the eye contacting the patientinterface such as a center of the limbus of the eye or centers ofcurvature of the lens of the eye, for example.

In many embodiments, one or more measurements of a cornea in asubstantially undistorted shape are used to determine parameters thatare used to determine locations of incisions of the cornea, such ascorneal incisions. The one or more measurements can be obtained in manyways, such as with images used for measuring corneal topography ortomography, or without imaging the eye. One or more additional imagescan be obtained when the one or more measurements are obtained, andthese one or more additional images can be used in combination with themeasurements for aligning the measurement coordinates and the cuttingcoordinates.

In many embodiments, a surface profile of the cornea is measured whenthe eye is placed in an undistorted shape, for example without being incontact with an external structure such as a patient interface, suchthat distortion of the cornea and measurement distortion issubstantially inhibited. When the eye has been placed in an undistortedconfiguration such as when the patient is supported with a patientsupport of the laser surgery system and views the fixation light, thecornea of the eye can be exposed to air with a tear film or other liquidover the cornea. The surface profile of the substantially undistortedcornea can be measured in one or more of many ways, and may comprise oneor more of an anterior corneal surface topography profile, a posterior acorneal surface topography profile, or a corneal thickness profile. Inmany embodiments, the surface profile comprises a representation of athree dimensional profile and may comprise an extraction of one or moreparameters from one or more images, such as an extraction of keratometryvalues from a corneal topography system or tomography system integratedwith the surgical laser. The one or more parameters can be used todetermine a tissue treatment pattern on the eye, such as the angularlocation, depth, arc length and anterior to posterior dimensions ofrelaxing incisions. Alternatively or in combination, a first image ofthe eye can be generated for aligning the eye such as a pupil image ofthe eye when the eye rests naturally and the surface profile ismeasured.

Subsequently, the eye can be contacted with a patient interface that mayat least partially distort the cornea. In many embodiments, a ring ofthe patient interface is coupled to the eye with suction, and the ringcan induce distortion of the cornea with mechanical coupling to thecornea. Additional components of the interface may induce additionaldistortion when an optically transmissive structure of the patientinterface contacts the cornea, or when the optically transmissivestructure is separated from the cornea with a liquid or viscoelasticmaterial, and combinations thereof. The first image can be compared witha second image in order to align the eye with the laser surgery system.

The first image or the one or more measurements, or both, can beobtained in one or more of many ways. In many embodiments, the one ormore measurements and the first image are obtained when the patient isplaced on a patient support of the laser eye surgery system, such as apatient bed of the laser eye surgery system. The laser eye surgerysystem may comprise biometry system such as a keratometer, topography ortomography system and the biometry system is used to obtain the cornealmeasurement to determine treatment parameters and the first image todetermine alignment when the patient is supported with the patientsupport of the laser eye surgery system. The first image may comprise aplurality of first images obtained together, such as a pupil image froma pupil camera and a corneal profile image from the biometery system.The one or more corneal measurements can be used to determine the one ormore treatment parameters such as a treatment axis when the patient issupported with the patient support.

When the cornea of the eye is covered with the patient interface, theimage of the eye may be at least partially distorted with the interface.In many embodiments, one or more of the second image of the eye or theeye itself can be distorted when liquid or viscoelastic material isplaced on the cornea to separate the cornea from an opticallytransmissive window or lens of the patient interface. The distortion canbe corrected in one or more of many ways and may comprise known amountsof distortion that can be corrected in the second image or combined withthe first image to provide a more accurate comparison of the first andsecond images, such that the patient can receive a more accuratetreatment.

With the patient interface coupled to the eye, the first image and thesecond image can be used in one or more of many ways to determine aposition and orientation of the eye coupled to the patient interface. Inmany embodiments, the distortion of the second image resulting frompatient interface comprises a determined distortion that can beincreased in the first image so that the first image looks like thesecond image and the second image shown on the display with the firstimage. Alternatively or in combination, distortion of the second imagecan be decreased from the second image so that the second image lookslike the first image. The distortion can be related to one or more ofimage magnification variation, translation of the image, rotation of theimage, mapping distortion of the imaging apparatus, or placement of theinterface over the eye. In many embodiments, the imaging apparatuscomprises a first amount of distortion prior to placement of the patientinterface over cornea and a second amount of distortion different fromthe first amount when the interface is placed over the eye, and one ormore of the first distortion or the second distortion can be used todetermine the mapping function to correct or distort the images. In manyembodiments, a mapping function can be used to map the first image tothe second image based on predetermined amounts of distortion. In manyembodiments, a laser eye surgery system comprises a processor, such as aprocessor system, and instructions of a computer program are stored on atangible medium comprising a computer memory. The instructions areconfigured to adjust one or more of the first image or second image inresponse to predetermined amounts of distortion, such as by mapping thefirst image to a distorted first image. The distorted first image can beprovided on a display for the physician to align with the second imageshown on the display. Alternatively or in combination, the alignment offirst and second images can be done with software algorithms, such asone or more of correlation or pattern recognition.

In a first aspect, a method of treating an eye of a patient is provided.A first image of the eye is generated when the eye is separated from thepatient interface such that the eye comprises a natural, undistortedstate. A ring of a patient interface can be coupled to the eye, and thecornea covered with an optic of the patient interface. A second image ofthe eye with the patient interface over the cornea is generated. In thissecond image, the patient interface alters distortion of the secondimage of the eye. In many embodiments, one or more of a position or anorientation of the eye is determined in response to the first image andthe second image when the patient interface has been placed over thecornea.

A shape profile of the cornea of the eye can be measured when at leastthe eye of the patient is supported with a patient support of a lasersurgery system. The shape profile can be measured and the first imagecan be generated before a suction ring of a patient interface is placedon the eye. The second image can be generated when the patient issupported with the patient support of the laser surgery system. Theshape profile can be used to determine an axis of treatment of anastigmatism of the eye. The shape profile can comprise one or more of akeratometry reading of the eye, a corneal topography of the eye, anoptical coherence tomography of the eye, a Placido disc topography ofthe eye, a reflection of a plurality of points from the corneatopography of the eye, a grid reflected from the cornea of the eyetopography, a Hartmann-Shack topography of the eye, a Scheimpflug imagetopography of the eye, a confocal tomography of the eye, or a lowcoherence reflectometry of the eye. The shape profile can be used todetermine an axis of treatment of a plurality of arcuate incisions, theplurality of arcuate incisions extending along an arc transverse to theaxis of treatment. Locations of the plurality of arcuate incisions canbe displayed on the second image of the eye distorted with the patientinterface. Locations of the plurality of arcuate incisions can be mappedfrom first locations of the first image to second locations of thesecond image with the second locations corresponding to distortion ofthe eye with the patient interface. The first image and the second imagemay be generated with a camera of the laser surgery system.

In many embodiments, the first image is modified to provide a distortedfirst image comprising distortion similar to the second image. Thedistorted first image can be provided on a display visible to a user. Auser can adjust one or more of a location or an angle of the firstdistorted image on the display. Locations of a plurality of laser beampulses can be adjusted in response to the location or the angle of thefirst distorted image on the display. The distorted first image can beoverlaid on the second image on the display to determine the positionand the angle of the eye for treatment. A processor can determine theposition and the angle of the distorted first image on the display inresponse to user input to adjust the locations of the plurality of laserbeam pulses.

In many embodiments, the second image is modified to provide a correctedsecond image comprising less distortion similar to the first image.

In many embodiments, the patient interface comprises a lighttransmissive optic disposed along an optical path with one or more of aliquid or a viscoelastic material disposed between the cornea and thelight transmissive optic. The optic and the one or more of the liquid orthe viscoelastic may distort the image of the eye.

In many embodiments, the first image comprises a plurality of imagestructures corresponding to a plurality of tissue structures of the eye.The plurality of image structures can be moved from a first plurality oflocations of the first image to a second plurality of locations of thedistorted first image in response to distortion of the patientinterface.

In many embodiments, the first image and the second image correspond toa coordinate reference of a laser treatment system. A plurality oflocations of the first image can be mapped from first locations of thecoordinate reference of the laser system to second locations of thecoordinate reference of the laser system to provide distortion of thefirst distorted image corresponding to distortion of the second image inorder to position the first distorted image in alignment with the secondimage.

In many embodiments, the first image and the second image correspond toa first coordinate reference of an ancillary diagnostic device and asecond coordinate reference of a laser treatment system, respectively. Aplurality of locations of the first image can be mapped from firstlocations of the first coordinate reference to second locations of thesecond coordinate reference of the laser system in order to determine ofthe position and the orientation of the eye with the patient interfaceover the cornea.

In many embodiments, the gas comprises air and the liquid comprises oneor more of a solution, saline or a viscoelastic fluid.

In many embodiments, the first image of the eye and the second image ofthe eye comprise images of an iris of the eye from a camera. One or morestructures of the first image and the second image may correspond to oneor more structures of the iris.

In many embodiments, the cornea exposed to the gas comprises a tearlayer.

In another aspect, an apparatus comprising a processor having a tangiblemedium configured to perform any combination of the method steps aboveis provided.

In yet another aspect, an apparatus for treating an eye having a corneais provided. The apparatus comprises a topography measurement system, animage capture device, a patient interface, and a processor. Thetopography measurement system measures a topography of the cornea of theeye. The image capture device captures an image of the eye. The patientinterface couples to and retains the eye. The processor comprises atangible medium configured to determine a position of the eye.

The topography measurement system may comprise one or more of akeratometry system, an optical coherence tomography system, a Placidodisc topography system, a Hartmann-Shack topography system, aScheimpflug image topography system, a confocal tomography system, or alow coherence reflectometry system. The patient interface may comprise asuction ring.

In many embodiments, the image capture device is configured to capture afirst image of the eye when the cornea is exposed to a gas and a secondimage of the eye with the patient interface over the cornea. Theprocessor comprising the tangible medium may be configured to determineone or more of a position or an orientation of the eye in response tothe first image and the second image when the patient interface has beenplaced over the cornea.

The topography measurement system may be configured to measure a shapeprofile of the cornea of the eye when at least the eye of the patient issupported with a patient support of a laser surgery system. The shapeprofile can be measured and the first image can be generated before asuction ring of a patient interface is placed on the eye. The secondimage can be generated when the patient is supported with the patientsupport of the laser surgery system. The shape profile can be used todetermine an axis of treatment of an astigmatism of the eye. The shapeprofile may comprise one or more of a keratometry reading of the eye, acorneal topography of the eye, an optical coherence tomography of theeye, a Placido disc topography of the eye, a reflection of a pluralityof points from the cornea topography of the eye, a grid reflected fromthe cornea of the eye topography, a Hartmann-Shack topography of theeye, a Scheimpflug image topography of the eye, a confocal tomography ofthe eye, or a low coherence reflectometry of the eye. The shape profilecan be used to determine an axis of treatment of a plurality of arcuateincisions, the plurality of arcuate incisions extending along an arctransverse to the axis of treatment. Locations of the plurality ofarcuate incisions can be displayed on the second image of the eyedistorted with the patient interface. Locations of the plurality ofarcuate incisions can be mapped from first locations of the first imageto second locations of the second image. The second locations maycorrespond to distortion of the eye with the patient interface. Thefirst image and the second image may be generated with a camera of thelaser surgery system.

The apparatus may further comprise a display visible to a user. Theprocessor comprising the tangible medium may be configured to modify thefirst image to provide a distorted first image comprising distortionsimilar to the second image and provide the distorted first image on thedisplay. The display can be configured to allow a user to adjust one ormore of a location or an angle of the first distorted image on thedisplay. Locations of a plurality of laser beam pulses can be adjustedin response to the location or the angle of the first distorted image onthe display. The distorted first image can be overlaid on the secondimage on the display to determine the position and the angle of the eyefor treatment. The processor comprising the tangible medium can beconfigured to determine the position and the angle of the distortedfirst image on the display in response to user input to adjust thelocations of the plurality of laser beam pulses.

In many embodiments, the processor comprising the tangible medium can beconfigured to modify the second image to provide a corrected secondimage comprising less distortion similar to the first image.

In many embodiments, the patient interface comprises a lighttransmissive optic disposed along an optical path with one or more of aliquid or a viscoelastic material disposed between the cornea and thelight transmissive optic. The optic and the one or more of the liquid orthe viscoelastic may distort the image of the eye.

In many embodiments, the first image comprises a plurality of imagestructures corresponding to a plurality of tissue structures of the eye.The plurality of image structures can be moved from a first plurality oflocations of the first image to a second plurality of locations of thedistorted first image in response to distortion of the patientinterface.

In many embodiments, the first image and the second image correspond toa coordinate reference of a laser treatment system. A plurality oflocations of the first image can be mapped from first locations of thecoordinate reference of the laser system to second locations of thecoordinate reference of the laser system to provide distortion of thefirst distorted image corresponding to distortion of the second image inorder to position the first distorted image in alignment with the secondimage.

In many embodiments, the first image and the second image correspond toa first coordinate reference of an ancillary diagnostic device and asecond coordinate reference of a laser treatment system, respectively. Aplurality of locations of the first image can be mapped from firstlocations of the first coordinate reference to second locations of thesecond coordinate reference of the laser system in order to determine ofthe position and the orientation of the eye with the patient interfaceover the cornea.

The gas the cornea may be exposed to may comprise air. The liquid thecornea may be exposed to may comprise one or more of a solution, salineor a viscoelastic fluid. The cornea exposed to the gas may comprise atear layer.

The first image of the eye and the second image of the eye may compriseimages of an iris of the eye from the image capture device. One or morestructures of the first image and the second image may correspond to oneor more structures of the iris.

In another aspect, embodiments provide method of measuring an eye. Themethod comprises coupling a corneal topography measurement structure toa patient interface structure to place the topography measurementstructure in front of the eye. The eye is measured with the topographymeasurement structure and the patient interface away from the eye. Thecorneal topography measurement structure is decoupled from the patientinterface structure. The patient interface structure is coupled to acomponent of the patient interface in order to contact the eye. Anastigmatism axis of the eye is determined in response to the measurementof the eye with the corneal topography structure removable coupled tothe patient interface.

In another aspect, embodiments provide an apparatus to measure an eye.The apparatus comprises a patient interface. A topography measurementstructure is configured to couple to the patient interface to measurethe eye without contacting the eye

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a perspective view showing a laser eye surgery system, inaccordance with many embodiments;

FIG. 2 shows a simplified block diagram showing a top level view of theconfiguration of a laser eye surgery system, in accordance with manyembodiments;

FIG. 3A shows a simplified block diagram illustrating the configurationof an optical assembly of a laser eye surgery system, in accordance withmany embodiments;

FIG. 3B shows a fixation light integrated into a fixed optical path of alaser system configured to illuminate the eye with externalillumination, in accordance with many embodiments;

FIG. 3C shows a mapped treatment region of the eye comprising thecornea, the posterior capsule, and the limbus, in accordance with manyembodiments;

FIG. 4A shows correspondence among movable and sensor components of thelaser delivery system, in accordance with many embodiments;

FIG. 4B shows mapping of coordinate references from an eye spacecoordinate reference system to a machine coordinate reference system, inaccordance with many embodiments; and

FIG. 5A shows a flow chart of a method for mapping the eye, inaccordance with many embodiments;

FIG. 5B shows a simplified block diagram showing a top level view of theconfiguration of a laser eye surgery system which can perform the methodof FIG. 5A, in accordance with many embodiments;

FIG. 6A shows a coordinate system overlaid on an image of the eye, inaccordance with many embodiments;

FIG. 6A1 shows corneal profile data for the coordinate system and imageof FIG. 6A;

FIG. 6A2 shows corneal thickness profile data for the coordinate systemand images of FIGS. 6A and 6A1;

FIG. 6A3 shows corneal thickness profile maps for the coordinate systemand images of FIGS. 6A, 6A1 and 6A2;

FIG. 6B shows a distorted coordinate system overlaid on the eye image ofFIG. 6A to account for distortions due coupling of the eye to a patientinterface, in accordance with many embodiments; and

FIG. 6C shows a distorted coordinate system overlaid on the eye image ofFIG. 6B to account for distortion due coupling of the eye to a patientinterface as well as liquid in the patient interface disposed over theeye, in accordance with many embodiments;

FIG. 6C1 shows corneal profile data for the coordinate system and imageof FIG. 6C;

FIG. 6C2 shows corneal thickness profile data for the coordinate systemand images of FIGS. 6C and 6C1;

FIG. 6C3 shows corneal thickness profile maps for the coordinate systemand images of FIGS. 6C, 6C1 and 6C2;

FIGS. 7A and 7B show side views of axes of the eye when the eye views afixation target and the eye is measured prior to contacting a patientinterface, in accordance with many embodiments;

FIG. 7C shows an anterior view of an eye as in FIGS. 7A and 7B, inaccordance with embodiments;

FIGS. 7D and 7E show the eye as in FIGS. 7A to 7C coupled to a patientinterface for treatment, in accordance with many embodiments;

FIG. 7F shows coordinate transformations of the measurement coordinatereference system prior to contacting the eye with the laser system andthe measurement coordinate reference system when the eye contacts thepatient interface as in FIGS. 7D and 7E;

FIG. 7G shows an optical schematic of the eye as in FIGS. 7A and 7B;

FIGS. 8A, 8B and 8C show images of a user interface display configuredto show one or more optical structures of the eye to position the laserbeam pulses of a tissue treatment in order to treat the eye, inaccordance with embodiments;

FIG. 9 shows an eye with an eccentric pupil, an offset fovea, anddetermination of an optical axis of the eye, in accordance withembodiments;

FIG. 10 shows a first optical axis of a non-contact measurement measuredwithout contact of the eye and an second optical axis of a contactmeasurement measured with a patient interface contacting the eye, inwhich the first and second optical axes can be used to determinelocations of structures of the eye when the eye contacts the patientinterface, in accordance with embodiments; and

FIG. 11A shows a topography measurement structure configured to coupleto a patient interface to measure the eye prior to the eye contactingthe patient interface, in accordance with embodiments;

FIG. 11B shows components of the patient interface and the topographymeasurement structure configured to couple to the patient interface, inaccordance with embodiments;

FIG. 11C shows a sectional view of the topography measurement structure;

FIG. 11D shows a perspective view of the interface end of the topographymeasurement structure;

FIG. 11E shows a perspective view of the working end of the topographymeasurement structure;

FIG. 12 shows a method of treating an eye with a laser beam, inaccordance with embodiments; and

FIG. 13 shows a corneal thickness profile map measured from a personwith an OCT system, in accordance with embodiments.

DETAILED DESCRIPTION

Methods and systems related to laser eye surgery are disclosed. In manyembodiments, a laser is used to form precise incisions in the cornea, inthe lens capsule, and/or in the crystalline lens nucleus. Althoughspecific reference is made to tissue retention for laser eye surgery,embodiments as described herein can be used in one or more of many wayswith many surgical procedures and devices, such as orthopedic surgery,robotic surgery and microkeratomes.

The embodiments as describe herein are particularly well suited fortreating tissue, such as with the surgical treatment of tissue. In manyembodiments, the tissue comprises an optically transmissive tissue, suchas tissue of an eye. The embodiments as described herein can be combinedin many ways with one or more of many known refractive surgicalprocedures such as cataract surgery, corneal incisions, including laserassisted in situ keratomileusis (hereinafter “LASIK”), all laser LASIK,femto LASIK, corneaplasty, astigmatic keratotomy, corneal relaxingincision (hereinafter “CRI”), Limbal Relaxing Incision (hereinafter“LRI”), photorefractive keratectomy (hereinafter “PRK”) and SmallIncision Lens Extraction (hereinafter “SMILE”), for example.

The embodiments as described herein are particularly well suited forcombination with intraocular lenses, for example with components of oneor more known intraocular lenses such as one or more of accommodatingintraocular lenses or intraocular lenses to correct aberrations of theeye, for example accommodating aberration correcting lenses of the eye.The embodiments disclosed herein can be used to combine refractivesurgical procedures with intraocular lenses, for example.

The embodiments as described herein can be used position to incisions ofthe lens capsule sized to receive structures of an intraocular lens inorder to retain the placed IOL in alignment with one or more axes theeye as described herein, for example in combination with lens capsulesand structures as described in U.S. Pat. App. Ser. No. 61/788,201, filedMar. 15, 2013, entitled “Microfemtotomy methods and systems” , theentire disclosure of which is incorporated herein by reference.

The embodiments as described herein can be used to position fiducialmarkings on the eye aligned with one or more axes of the eye asdescribed herein in order to align an axis of an IOL with the eye, forexample in combination with fiducial markings and lenses as described inU.S. Ser. No. 61/813,172, filed Apr. 17, 2013, entitled “Laser fiducialsfor alignment in cataract surgery (attorney docket number U.S.43406-747.101)

Methods and systems related to laser treatment of materials and whichcan be used with eye surgery such as laser eye surgery are disclosed. Alaser may be used to form precise incisions in the cornea, in the lenscapsule, and/or in the crystalline lens nucleus, for example. Theembodiments as described herein can be particularly well suited forincreasing the accuracy of the cutting of the material such as tissue,for example.

In many embodiments, a patient interface coupled to the eye influencesdistortion of images and measurements of the eye obtained through thepatient interface. The patient interface may comprise a suction ringthat can be placed on the eye near the limbus, and placement of thesuction ring on the eye can influence distortion of the cornea. Thepatient interface may comprise an optically transmissive structure suchas a flat plate or lens, and the optically transmissive structure caninfluence distortion of the second image. For example, the patientinterface may add barrel distortion to images of the eye taken throughthe patient interface as compared with images of the eye taken when thepatient interface has been separated from the eye and the eye comprisesa natural configuration. Alternatively, the patient interface bedesigned to add pincushion distortion, for example. The embodimentsdisclosed herein are particularly well suited for combination with apatient interface having an optically transmissive element separatedfrom the cornea. The curved lower surface of the optically transmissivelens structure separated from the cornea to urge gas bubbles away fromthe optical axis can increase the depth of field and range of thetreatment, and the embodiments disclosed herein are ideally suited foruse with such a patient interface.

The embodiments disclosed herein also suited for combination withcorneal measurement systems. The corneal measurement system may comprisea component of the laser surgery system, which allows the cornea to bemeasured with the corneal measurement system when the patient issupported with a patient support such as a bed of the laser surgerysystem. Alternatively, the corneal measurement system may comprise acorneal measurement system separated from the laser system, such as inanother room of a physician's office.

The embodiments disclosed herein are well suited for combination withprior laser surgery systems, such as Catalys™ commercially availablefrom Optimedica, and similar systems. Such systems can be modified inaccordance with the teachings disclosed herein and to more accuratelymeasure and treat the eye.

As used herein like characters such as reference numerals and lettersdescribed like elements.

As used herein, the terms anterior and posterior refers to knownorientations with respect to the patient. Depending on the orientationof the patient for surgery, the terms anterior and posterior may besimilar to the terms upper and lower, respectively, such as when thepatient is placed in a supine position on a bed. The terms distal andanterior may refer to an orientation of a structure from the perspectiveof the user, such that the terms proximal and distal may be similar tothe terms anterior and posterior when referring to a structure placed onthe eye, for example. A person of ordinary skill in the art willrecognize many variations of the orientation of the methods andapparatus as described herein, and the terms anterior, posterior,proximal, distal, upper, and lower are used merely by way of example.

As used herein, the terms first and second are used to describestructures and methods without limitation as to the order of thestructures and methods which can be in any order, as will be apparent toa person of ordinary skill in the art based on the teachings providedherein.

As used herein the term anterior and posterior nodal points of the eyemay have the property that a ray aimed at one node will be refracted bythe eye such that it appears to have come from the other node, and withthe same angle with respect to the optical axis.

The embodiments disclosed herein enable accurate and substantiallydistortion-free corneal topography measurement and subsequentintegration with the laser treatment. In many embodiments, means foraccomplishing at least three steps are provided:

1. Positioning the patient eye within the capture range of themeasurement system;

2. A measurement system that is capable of accurately measuring thecorneal; and

3. Correcting for one or more of many changes in the patient eyeorientation that may occur between the measurement time and the lasertreatment time.

Positioning

In many embodiments, positioning of the patient for laser surgery isprovided by motion of the patient bed or by motion of the laser system.The operator has manual control of the lateral and axial position,guiding the docking mechanism into place. In the absence of a dockingmechanism, the operator can be provided with means for guiding themotion so that the eye, such that the cornea is placed within theoperative range of the measurement system. This can be accomplished withthe subsystems of Catalys™ and similar systems, with some modificationsin accordance with embodiments disclosed herein. Initial patientposition can be guided by the video camera, in order to guide the eyeinto lateral position by centering the video image and into axialposition by focusing the image with the video camera, for example. Atthe completion of this step the cornea is within the capture range ofthe tomography system. The tomography system may comprise one or more ofmany tomography systems as described herein, and may comprise an opticalcoherence tomography system (hereinafter “OCT” system), a Scheimpflugimaging system, a low coherence reflectometry system, or a scanningconfocal spot imaging system, for example. The tomography system such asthe OCT system is used to measure the axial position of the cornea, anda suitable display provides the operator guidance for final, accuratepositioning.

In many embodiments, the video and OCT systems are configured to operatewith the docking system, which has additional optical elements andliquid medium in the optics path, it may be helpful to adjust thefocusing algorithms of the laser system to account for operation withoutthe docking mechanism optics and interface medium such as a liquid orviscoelastic.

Measurement

In many embodiments, the laser system has a subsystem for mapping theocular surfaces that are being treated, such as with tomography asdescribed herein. The measurement step is preferable done when the eyehas been positioned correctly. A fixation light can optionally beintroduced to help the patient keep the eye pointed at in a fixeddirection at a fixed angle. If the measurement data capture is fastenough, on the order of one second for example, a fixation light may notbe as beneficial. Multiple tomography scans, such as OCT, of the corneasurfaces can be acquired in a short time. Multiple scans increase theaccuracy of the data, and can provide topography data of the cornea.Post processing of the scans may be used to remove potential eye motionand improves the measurement accuracy.

When the corneal surfaces have been mapped, polynomial fittingalgorithms or other fitting algorithms can be used to calculate usefulparameters of the cornea such as one or more of the optical power of thecornea, the astigmatic axis angle, and astigmatism magnitude, forexample.

Examples of fitting algorithms suitable for mapping optical tissuesurfaces include elliptical surfaces, Fourier transforms, polynomials, aspherical harmonics, Taylor polynomials, a wavelet transform, or Zernikepolynomials. In many embodiments, three dimensional elevation profiledata of an optical tissue surface of the eye is provided, and the datafit to the optical tissue surface. The optical tissue surface maycomprise one or more of the anterior surface of the cornea, theposterior surface of the cornea, the anterior surface of the lenscapsule, the posterior surface of the lens capsule, an anterior surfaceof the lens cortex, a posterior surface of the lens cortex, an anteriorsurface of the lens nucleus, a posterior surface of the lens nucleus,one or more anterior surfaces of the lens having a substantiallyconstant index of refraction, one or more posterior surfaces of the lenshaving a substantially constant index of refraction, the retinalsurface, the foveal surface, a target tissue surface to correct visionsuch as a target corneal surface, an anterior surface of an intraocularlens, or a posterior surface of an intraocular lens, for example. As theindex of refraction of the lens can vary from about 1.36 to about 1.41,optical surfaces of the lens may define one or more layers of the lenshaving a similar index of refraction, for example.

Coordinate System Transfer

In many embodiments, when the patient eye is docked for treatment, theeye changes one or more of position or rotation relative to the lasersystem coordinates. The position may comprise three positionaldimensions, and the rotation may comprise three rotational dimensions,and the change in position or orientation may comprise all six degreesof freedom in at least some embodiments. This change in one or more ofposition or orientation can be a result of patient head movement, eyemovement, or related to force applied during docking of the eye with thepatient interface. It may be helpful to transform the cornealmeasurements, like the astigmatic axis angle, to the new coordinatesystem. There are several methods for accomplishing this.

One method allows the operator to mark the patient eye, prior to themeasurement, with ink dots that are typically positioned diametricallyacross on the periphery of the cornea. These dots can be acquired by theimaging camera after docking for treatment and used for calculating thecoordinate transformation.

Another method is to use ocular features that are visible in the videoimages, or the OCT scans, taken during the corneal measurement step andto determine the position and orientation of the eye. This determinationcan be made with correlation for example, or identification for example,of the features of the first image in relation to features of the secondimage taken after docking for treatment. This identification orcorrelation can be done by digital image processing algorithms, ormanually by the operator. When done manually the operator is presentedby overlapped images (measurement and treatment steps) on the displayscreen, and the images are manually manipulated in translation androtation until they are visibly matched. The image manipulation data isdetected by the display software and used for the coordinate transform.

The processor system may comprise tangible medium embodying instructionsof a computer program to perform one or more of the method steps asdescribed herein.

FIG. 1 shows a laser eye surgery system 2, in accordance with manyembodiments, operable to form precise incisions in the cornea, in thelens capsule, and/or in the crystalline lens nucleus. The system 2includes a main unit 4, a patient chair 6, a dual function footswitch 8,and a laser footswitch 10.

The main unit 4 includes many primary subsystems of the system 2. Forexample, externally visible subsystems include a touch-screen displaycontrol panel 12, a patient interface assembly 14, patient interfacevacuum connections 16, a docking control keypad 18, a patient interfaceradio frequency identification (RFID) reader 20, external connections 22(e.g., network, video output, footswitch, USB port, door interlock, andAC power), laser emission indicator 24, emergency laser stop button 26,key switch 28, and USB data ports 30.

The patient chair 6 includes a base 32, a patient support bed 34, aheadrest 36, a positioning mechanism, and a patient chair joystickcontrol 38 disposed on the headrest 36. The positioning controlmechanism is coupled between the base 32 and the patient support bed 34and headrest 36. The patient chair 6 is configured to be adjusted andoriented in three axes (x, y, and z) using the patient chair joystickcontrol 38. The headrest 36 and a restrain system (not shown, e.g., arestraint strap engaging the patient's forehead) stabilize the patient'shead during the procedure. The headrest 36 includes an adjustable necksupport to provide patient comfort and to reduce patient head movement.The headrest 36 is configured to be vertically adjustable to enableadjustment of the patient head position to provide patient comfort andto accommodate variation in patient head size.

The patient chair 6 allows for tilt articulation of the patient's legs,torso, and head using manual adjustments. The patient chair 6accommodates a patient load position, a suction ring capture position,and a patient treat position. In the patient load position, the chair 6is rotated out from under the main unit 4 with the patient chair back inan upright position and patient footrest in a lowered position. In thesuction ring capture position, the chair is rotated out from under themain unit 4 with the patient chair back in reclined position and patientfootrest in raised position. In the patient treat position, the chair isrotated under the main unit 4 with the patient chair back in reclinedposition and patient footrest in raised position.

The patient chair 6 is equipped with a “chair enable” feature to protectagainst unintended chair motion. The patient chair joystick 38 can beenabled in either of two ways. First, the patient chair joystick 38incorporates a “chair enable” button located on the top of the joystick.Control of the position of the patient chair 6 via the joystick 38 canbe enabled by continuously pressing the “chair enable” button.Alternately, the left foot switch 40 of the dual function footswitch 8can be continuously depressed to enable positional control of thepatient chair 6 via the joystick 38.

In many embodiments, the patient control joystick 38 is a proportionalcontroller. For example, moving the joystick a small amount can be usedto cause the chair to move slowly. Moving the joystick a large amountcan be used to cause the chair to move faster. Holding the joystick atits maximum travel limit can be used to cause the chair to move at themaximum chair speed. The available chair speed can be reduced as thepatient approaches the patient interface assembly 14.

The emergency stop button 26 can be pushed to stop emission of all laseroutput, release vacuum that couples the patient to the system 2, anddisable the patient chair 6. The stop button 26 is located on the systemfront panel, next to the key switch 28.

The key switch 28 can be used to enable the system 2. When in a standbyposition, the key can be removed and the system is disabled. When in aready position, the key enables power to the system 2.

The dual function footswitch 8 is a dual footswitch assembly thatincludes the left foot switch 40 and a right foot switch 42. The leftfoot switch 40 is the “chair enable” footswitch. The right footswitch 42is a “vacuum ON” footswitch that enables vacuum to secure a liquidoptics interface suction ring to the patient's eye. The laser footswitch10 is a shrouded footswitch that activates the treatment laser whendepressed while the system is enabled.

In many embodiments, the system 2 includes external communicationconnections. For example, the system 2 can include a network connection(e.g., an RJ45 network connection) for connecting the system 2 to anetwork. The network connection can be used to enable network printingof treatment reports, remote access to view system performance logs, andremote access to perform system diagnostics. The system 2 can include avideo output port (e.g., HDMI) that can be used to output video oftreatments performed by the system 2. The output video can be displayedon an external monitor for, for example, viewing by family membersand/or training. The output video can also be recorded for, for example,archival purposes. The system 2 can include one or more data outputports (e.g., USB) to, for example, enable export of treatment reports toa data storage device. The treatments reports stored on the data storagedevice can then be accessed at a later time for any suitable purposesuch as, for example, printing from an external computer in the casewhere the user without access to network based printing.

FIG. 2 shows a simplified block diagram of the system 2 coupled with apatient eye 43. The patient eye 43 comprises a cornea 43C, a lens 43Land an iris 43I. The iris 43I defines a pupil of the eye 43 that may beused for alignment of eye 43 with system 2. The system 2 includes acutting laser subsystem 44, a ranging subsystem 46, an alignmentguidance system 48, shared optics 50, a patient interface 52, controlelectronics 54, a control panel/GUI 56, user interface devices 58, andcommunication paths 60. The control electronics 54 is operativelycoupled via the communication paths 60 with the cutting laser subsystem44, the ranging subsystem 46, the alignment guidance subsystem 48, theshared optics 50, the patient interface 52, the control panel/GUI 56,and the user interface devices 58.

In many embodiments, the cutting laser subsystem 44 incorporatesfemtosecond (FS) laser technology. By using femtosecond lasertechnology, a short duration (e.g., approximately 10⁻¹³ seconds induration) laser pulse (with energy level in the micro joule range) canbe delivered to a tightly focused point to disrupt tissue, therebysubstantially lowering the energy level required as compared to thelevel required for ultrasound fragmentation of the lens nucleus and ascompared to laser pulses having longer durations.

The cutting laser subsystem 44 can produce laser pulses having awavelength suitable to the configuration of the system 2. As anon-limiting example, the system 2 can be configured to use a cuttinglaser subsystem 44 that produces laser pulses having a wavelength from1020 nm to 1050 nm. For example, the cutting laser subsystem 44 can havea diode-pumped solid-state configuration with a 1030 (+/−5) nm centerwavelength.

The cutting laser subsystem 44 can include control and conditioningcomponents. For example, such control components can include componentssuch as a beam attenuator to control the energy of the laser pulse andthe average power of the pulse train, a fixed aperture to control thecross-sectional spatial extent of the beam containing the laser pulses,one or more power monitors to monitor the flux and repetition rate ofthe beam train and therefore the energy of the laser pulses, and ashutter to allow/block transmission of the laser pulses. Suchconditioning components can include an adjustable zoom assembly to adaptthe beam containing the laser pulses to the characteristics of thesystem 2 and a fixed optical relay to transfer the laser pulses over adistance while accommodating laser pulse beam positional and/ordirectional variability, thereby providing increased tolerance forcomponent variation.

The ranging subsystem 46 is configured to measure the spatialdisposition of eye structures in three dimensions. The measured eyestructures can include the anterior and posterior surfaces of thecornea, the anterior and posterior portions of the lens capsule, theiris, and the limbus. In many embodiments, the ranging subsystem 46utilizes optical coherence tomography (OCT) imaging. As a non-limitingexample, the system 2 can be configured to use an OCT imaging systememploying wavelengths from 780 nm to 970 nm. For example, the rangingsubsystem 46 can include an OCT imaging system that employs a broadspectrum of wavelengths from 810 nm to 850 nm. Such an OCT imagingsystem can employ a reference path length that is adjustable to adjustthe effective depth in the eye of the OCT measurement, thereby allowingthe measurement of system components including features of the patientinterface that lie anterior to the cornea of the eye and structures ofthe eye that range in depth from the anterior surface of the cornea tothe posterior portion of the lens capsule and beyond.

The alignment guidance subsystem 48 can include a laser diode or gaslaser that produces a laser beam used to align optical components of thesystem 2. The alignment guidance subsystem 48 can include LEDs or lasersthat produce a fixation light to assist in aligning and stabilizing thepatient's eye during docking and treatment. The alignment guidancesubsystem 48 can include a laser or LED light source and a detector tomonitor the alignment and stability of the actuators used to positionthe beam in X, Y, and Z. The alignment guidance subsystem 48 can includea video system that can be used to provide imaging of the patient's eyeto facilitate docking of the patient's eye 43 to the patient interface52. The imaging system provided by the video system can also be used todirect via the GUI the location of cuts. The imaging provided by thevideo system can additionally be used during the laser eye surgeryprocedure to monitor the progress of the procedure, to track movementsof the patient's eye 43 during the procedure, and to measure thelocation and size of structures of the eye such as the pupil and/orlimbus.

The shared optics 50 provides a common propagation path that is disposedbetween the patient interface 52 and each of the cutting laser subsystem44, the ranging subsystem 46, and the alignment guidance subsystem 48.In many embodiments, the shared optics 50 includes beam combiners toreceive the emission from the respective subsystem (e.g., the cuttinglaser subsystem 44, and the alignment guidance subsystem 48) andredirect the emission along the common propagation path to the patientinterface. In many embodiments, the shared optics 50 includes anobjective lens assembly that focuses each laser pulse into a focalpoint. In many embodiments, the shared optics 50 includes scanningmechanisms operable to scan the respective emission in three dimensions.For example, the shared optics can include an XY-scan mechanism(s) and aZ-scan mechanism. The XY-scan mechanism(s) can be used to scan therespective emission in two dimensions transverse to the propagationdirection of the respective emission. The Z-scan mechanism can be usedto vary the depth of the focal point within the eye 43. In manyembodiments, the scanning mechanisms are disposed between the laserdiode and the objective lens such that the scanning mechanisms are usedto scan the alignment laser beam produced by the laser diode. Incontrast, in many embodiments, the video system is disposed between thescanning mechanisms and the objective lens such that the scanningmechanisms do not affect the image obtained by the video system.

The patient interface 52 is used to restrain the position of thepatient's eye 43 relative to the system 2. In many embodiments, thepatient interface 52 employs a suction ring that is vacuum attached tothe patient's eye 43. The suction ring is then coupled with the patientinterface 52, for example, using vacuum to secure the suction ring tothe patient interface 52. In many embodiments, the patient interface 52includes an optically transmissive structure having a posterior surfacethat is displaced vertically from the anterior surface of the patient'scornea and a region of a suitable liquid (e.g., a sterile bufferedsaline solution (BSS) such as Alcon BSS (Alcon Part Number 351-55005-1)or equivalent) is disposed between and in contact with the patientinterface lens posterior surface and the patient's cornea and forms partof a transmission path between the shared optics 50 and the patient'seye 43. The optically transmissive structure may comprise a lens 96having one or more curved surfaces. Alternatively, the patient interface22 may comprise an optically transmissive structure having one or moresubstantially flat surfaces such as a parallel plate or wedge. In manyembodiments, the patient interface lens is disposable and can bereplaced at any suitable interval, such as before each eye treatment.

The control electronics 54 controls the operation of and can receiveinput from the cutting laser subsystem 44, the ranging subsystem 46, thealignment guidance subsystem 48, the patient interface 52, the controlpanel/GUI 56, and the user interface devices 58 via the communicationpaths 60. The communication paths 60 can be implemented in any suitableconfiguration, including any suitable shared or dedicated communicationpaths between the control electronics 54 and the respective systemcomponents. The control electronics 54 can include any suitablecomponents, such as one or more processor, one or morefield-programmable gate array (FPGA), and one or more memory storagedevices. In many embodiments, the control electronics 54 controls thecontrol panel/GUI 56 to provide for pre-procedure planning according touser specified treatment parameters as well as to provide user controlover the laser eye surgery procedure.

The user interface devices 58 can include any suitable user input devicesuitable to provide user input to the control electronics 54. Forexample, the user interface devices 58 can include devices such as, forexample, the dual function footswitch 8, the laser footswitch 10, thedocking control keypad 18, the patient interface radio frequencyidentification (RFID) reader 20, the emergency laser stop button 26, thekey switch 28, and the patient chair joystick control 38.

FIG. 3A is a simplified block diagram illustrating an assembly 62, inaccordance with many embodiments, that can be included in the system 2.The assembly 62 is a non-limiting example of suitable configurations andintegration of the cutting laser subsystem 44, the ranging subsystem 46,the alignment guidance subsystem 48, the shared optics 50, and thepatient interface 52. Other configurations and integration of thecutting laser subsystem 44, the ranging subsystem 46, the alignmentguidance subsystem 48, the shared optics 50, and the patient interface52 may be possible and may be apparent to a person of skill in the art.

The assembly 62 is operable to project and scan optical beams into thepatient's eye 43. The cutting laser subsystem 44 includes an ultrafast(UF) laser 64 (e.g., a femtosecond laser). Using the assembly 62,optical beams can be scanned in the patient's eye 43 in threedimensions: X, Y, Z. For example, short-pulsed laser light generated bythe UF laser 64 can be focused into eye tissue to produce dielectricbreakdown to cause photodisruption around the focal point (the focalzone), thereby rupturing the tissue in the vicinity of the photo-inducedplasma. In the assembly 62, the wavelength of the laser light can varybetween 800 nm to 1200 nm and the pulse width of the laser light canvary from 10 fs to 10000 fs. The pulse repetition frequency can alsovary from 10 kHz to 500 kHz. Safety limits with regard to unintendeddamage to non-targeted tissue bound the upper limit with regard torepetition rate and pulse energy. Threshold energy, time to complete theprocedure, and stability can bound the lower limit for pulse energy andrepetition rate. The peak power of the focused spot in the eye 43 andspecifically within the crystalline lens and the lens capsule of the eyeis sufficient to produce optical breakdown and initiate aplasma-mediated ablation process. Near-infrared wavelengths for thelaser light are preferred because linear optical absorption andscattering in biological tissue is reduced for near-infraredwavelengths. As an example, the laser 64 can be a repetitively pulsed1031 nm device that produces pulses with less than 600 fs duration at arepetition rate of 120 kHz (+/−5%) and individual pulse energy in the 1to 20 micro joule range.

The cutting laser subsystem 44 is controlled by the control electronics54 and the user, via the control panel/GUI 56 and the user interfacedevices 58, to create a laser pulse beam 66. The control panel/GUI 56 isused to set system operating parameters, process user input, displaygathered information such as images of ocular structures, and displayrepresentations of incisions to be formed in the patient's eye 43.

The generated laser pulse beam 66 proceeds through a zoom assembly 68.The laser pulse beam 66 may vary from unit to unit, particularly whenthe UF laser 64 may be obtained from different laser manufacturers. Forexample, the beam diameter of the laser pulse beam 66 may vary from unitto unit (e.g., by +/−20%). The beam may also vary with regard to beamquality, beam divergence, beam spatial circularity, and astigmatism. Inmany embodiments, the zoom assembly 68 is adjustable such that the laserpulse beam 66 exiting the zoom assembly 68 has consistent beam diameterand divergence unit to unit.

After exiting the zoom assembly 68, the laser pulse beam 66 proceedsthrough an attenuator 70. The attenuator 70 is used to adjust thetransmission of the laser beam and thereby the energy level of the laserpulses in the laser pulse beam 66. The attenuator 70 is controlled viathe control electronics 54.

After exiting the attenuator 70, the laser pulse beam 66 proceedsthrough an aperture 72. The aperture 72 sets the outer useful diameterof the laser pulse beam 66. In turn the zoom determines the size of thebeam at the aperture location and therefore the amount of light that istransmitted. The amount of transmitted light is bounded both high andlow. The upper is bounded by the requirement to achieve the highestnumerical aperture achievable in the eye. High NA promotes low thresholdenergies and greater safety margin for untargeted tissue. The lower isbound by the requirement for high optical throughput. Too muchtransmission loss in the system shortens the lifetime of the system asthe laser output and system degrades over time. Additionally,consistency in the transmission through this aperture promotes stabilityin determining optimum settings (and sharing of) for each procedure.Typically to achieve optimal performance the transmission through thisaperture as set to be between 88% to 92%.

After exiting the aperture 72, the laser pulse beam 66 proceeds throughtwo output pickoffs 74. Each output pickoff 74 can include a partiallyreflecting mirror to divert a portion of each laser pulse to arespective output monitor 76. Two output pickoffs 74 (e.g., a primaryand a secondary) and respective primary and secondary output monitors 76are used to provide redundancy in case of malfunction of the primaryoutput monitor 76.

After exiting the output pickoffs 74, the laser pulse beam 66 proceedsthrough a system-controlled shutter 78. The system-controlled shutter 78ensures on/off control of the laser pulse beam 66 for procedural andsafety reasons. The two output pickoffs precede the shutter allowing formonitoring of the beam power, energy, and repetition rate as apre-requisite for opening the shutter.

After exiting the system-controlled shutter 78, the optical beamproceeds through an optics relay telescope 80. The optics relaytelescope 80 propagates the laser pulse beam 66 over a distance whileaccommodating positional and/or directional variability of the laserpulse beam 66, thereby providing increased tolerance for componentvariation. As an example, the optical relay can be a keplerian afocaltelescope that relays an image of the aperture position to a conjugateposition near to the xy galvo mirror positions. In this way, theposition of the beam at the XY galvo location is invariant to changes inthe beams angle at the aperture position. Similarly the shutter does nothave to precede the relay and may follow after or be included within therelay.

After exiting the optics relay telescope 80, the laser pulse beam 66 istransmitted to the shared optics 50, which propagates the laser pulsebeam 66 to the patient interface 52. The laser pulse beam 66 is incidentupon a beam combiner 82, which reflects the laser pulse beam 66 whiletransmitting optical beams from the ranging subsystem 46 and thealignment guidance subsystem: AIM 48.

Following the beam combiner 82, the laser pulse beam 66 continuesthrough a Z-telescope 84, which is operable to scan focus position ofthe laser pulse beam 66 in the patient's eye 43 along the Z axis. Forexample, the Z-telescope 84 can include a Galilean telescope with twolens groups (each lens group includes one or more lenses). One of thelens groups moves along the Z axis about the collimation position of theZ-telescope 84. In this way, the focus position of the spot in thepatient's eye 43 moves along the Z axis. In general, there is arelationship between the motion of lens group and the motion of thefocus point. For example, the Z-telescope can have an approximate 2×beam expansion ratio and close to a 1:1 relationship of the movement ofthe lens group to the movement of the focus point. The exactrelationship between the motion of the lens and the motion of the focusin the z axis of the eye coordinate system does not have to be a fixedlinear relationship. The motion can be nonlinear and directed via amodel or a calibration from measurement or a combination of both.Alternatively, the other lens group can be moved along the Z axis toadjust the position of the focus point along the Z axis. The Z-telescope84 functions as z-scan device for scanning the focus point of thelaser-pulse beam 66 in the patient's eye 43. The Z-telescope 84 can becontrolled automatically and dynamically by the control electronics 54and selected to be independent or to interplay with the X and Y scandevices described next.

After passing through the Z-telescope 84, the laser pulse beam 66 isincident upon an X-scan device 86, which is operable to scan the laserpulse beam 66 in the X direction, which is dominantly transverse to theZ axis and transverse to the direction of propagation of the laser pulsebeam 66. The X-scan device 86 is controlled by the control electronics54, and can include suitable components, such as a motor, galvanometer,or any other well known optic moving device. The relationship of themotion of the beam as a function of the motion of the X actuator doesnot have to be fixed or linear. Modeling or calibrated measurement ofthe relationship or a combination of both can be determined and used todirect the location of the beam.

After being directed by the X-scan device 86, the laser pulse beam 66 isincident upon a Y-scan device 88, which is operable to scan the laserpulse beam 66 in the Y direction, which is dominantly transverse to theX and Z axes. The Y-scan device 88 is controlled by the controlelectronics 54, and can include suitable components, such as a motor,galvanometer, or any other well known optic moving device. Therelationship of the motion of the beam as a function of the motion ofthe Y actuator does not have to be fixed or linear. Modeling orcalibrated measurement of the relationship or a combination of both canbe determined and used to direct the location of the beam.Alternatively, the functionality of the X-Scan device 86 and the Y-Scandevice 88 can be provided by an XY-scan device configured to scan thelaser pulse beam 66 in two dimensions transverse to the Z axis and thepropagation direction of the laser pulse beam 66. The X-scan and Y-scandevices 86, 88 change the resulting direction of the laser pulse beam66, causing lateral displacements of UF focus point located in thepatient's eye 43.

After being directed by the Y-scan device 88, the laser pulse beam 66passes through a beam combiner 90. The beam combiner 90 is configured totransmit the laser pulse beam 66 while reflecting optical beams to andfrom a video subsystem 92 of the alignment guidance subsystem 48.

After passing through the beam combiner 90, the laser pulse beam 66passes through an objective lens assembly 94. The objective lensassembly 94 can include one or more lenses. In many embodiments, theobjective lens assembly 94 includes multiple lenses. The complexity ofthe objective lens assembly 94 may be driven by the scan field size, thefocused spot size, the degree of telecentricity, the available workingdistance on both the proximal and distal sides of objective lensassembly 94, as well as the amount of aberration control.

After passing through the objective lens assembly 94, the laser pulsebeam 66 passes through the patient interface 52. As described above, inmany embodiments, the patient interface 52 includes a patient interfacelens 96 having a posterior surface that is displaced vertically from theanterior surface of the patient's cornea and a region of a suitableliquid (e.g., a sterile buffered saline solution (BSS) such as Alcon BSS(Alcon Part Number 351-55005-1) or equivalent) is disposed between andin contact with the posterior surface of the patient interface lens 96and the patient's cornea and forms part of an optical transmission pathbetween the shared optics 50 and the patient's eye 43.

The shared optics 50 under the control of the control electronics 54 canautomatically generate aiming, ranging, and treatment scan patterns.Such patterns can be comprised of a single spot of light, multiple spotsof light, a continuous pattern of light, multiple continuous patterns oflight, and/or any combination of these. In addition, the aiming pattern(using the aim beam 108 described below) need not be identical to thetreatment pattern (using the laser pulse beam 66), but can optionally beused to designate the boundaries of the treatment pattern to provideverification that the laser pulse beam 66 will be delivered only withinthe desired target area for patient safety. This can be done, forexample, by having the aiming pattern provide an outline of the intendedtreatment pattern. This way the spatial extent of the treatment patterncan be made known to the user, if not the exact locations of theindividual spots themselves, and the scanning thus optimized for speed,efficiency, and/or accuracy. The aiming pattern can also be made to beperceived as blinking in order to further enhance its visibility to theuser. Likewise, the ranging beam 102 need not be identical to thetreatment beam or pattern. The ranging beam needs only to be sufficientenough to identify targeted surfaces. These surfaces can include thecornea and the anterior and posterior surfaces of the lens and may beconsidered spheres with a single radius of curvature. Also the opticsshared by the alignment guidance: video subsystem does not have to beidentical to those shared by the treatment beam. The positioning andcharacter of the laser pulse beam 66 and/or the scan pattern the laserpulse beam 66 forms on the eye 43 may be further controlled by use of aninput device such as a joystick, or any other appropriate user inputdevice (e.g., control panel/GUI 56) to position the patient and/or theoptical system.

The control electronics 54 can be configured to target the targetedstructures in the eye 43 and ensure that the laser pulse beam 66 will befocused where appropriate and not unintentionally damage non-targetedtissue. Imaging modalities and techniques described herein, such asthose mentioned above, or ultrasound may be used to determine thelocation and measure the thickness of the lens and lens capsule toprovide greater precision to the laser focusing methods, including 2Dand 3D patterning. Laser focusing may also be accomplished by using oneor more methods including direct observation of an aiming beam, or otherknown ophthalmic or medical imaging modalities, such as those mentionedabove, and/or combinations thereof. Additionally the ranging subsystemsuch as an OCT can be used to detect features or aspects involved withthe patient interface. Features can include fiducials places on thedocking structures and optical structures of the disposable lens such asthe location of the anterior and posterior surfaces.

In the embodiment of FIG. 3, the ranging subsystem 46 includes an OCTimaging device. Additionally or alternatively, imaging modalities otherthan OCT imaging can be used. An OCT scan of the eye can be used tomeasure the spatial disposition (e.g., three dimensional coordinatessuch as X, Y, and Z of points on boundaries) of structures of interestin the patient's eye 43. Such structure of interest can include, forexample, the anterior surface of the cornea, the posterior surface ofthe cornea, the anterior portion of the lens capsule, the posteriorportion of the lens capsule, the anterior surface of the crystallinelens, the posterior surface of the crystalline lens, the iris, thepupil, and/or the limbus. The spatial disposition of the structures ofinterest and/or of suitable matching geometric modeling such as surfacesand curves can be generated and/or used by the control electronics 54 toprogram and control the subsequent laser-assisted surgical procedure.The spatial disposition of the structures of interest and/or of suitablematching geometric modeling can also be used to determine a wide varietyof parameters related to the procedure such as, for example, the upperand lower axial limits of the focal planes used for cutting the lenscapsule and segmentation of the lens cortex and nucleus, and thethickness of the lens capsule among others.

The ranging subsystem 46 in FIG. 3 includes an OCT light source anddetection device 98. The OCT light source and detection device 98includes a light source that generates and emits light with a suitablebroad spectrum. For example, in many embodiments, the OCT light sourceand detection device 98 generates and emits light with a broad spectrumfrom 810 nm to 850 nm wavelength. The generated and emitted light iscoupled to the device 98 by a single mode fiber optic connection.

The light emitted from the OCT light source and detection device 98 ispassed through a beam combiner 100, which divides the light into asample portion 102 and a reference portion 104. A significant portion ofthe sample portion 102 is transmitted through the shared optics 50. Arelative small portion of the sample portion is reflected from thepatient interface 52 and/or the patient's eye 43 and travels backthrough the shared optics 50, back through the beam combiner 100 andinto the OCT light source and detection device 98. The reference portion104 is transmitted along a reference path 106 having an adjustable pathlength. The reference path 106 is configured to receive the referenceportion 104 from the beam combiner 100, propagate the reference portion104 over an adjustable path length, and then return the referenceportion 106 back to the beam combiner 100, which then directs thereturned reference portion 104 back to the OCT light source anddetection device 98. The OCT light source and detection device 98 thendirects the returning small portion of the sample portion 102 and thereturning reference portion 104 into a detection assembly, which employsa time domain detection technique, a frequency detection technique, or asingle point detection technique. For example, a frequency-domaintechnique can be used with an OCT wavelength of 830 nm and bandwidth of10 nm.

Once combined with the UF laser pulse beam 66 subsequent to the beamcombiner 82, the OCT sample portion beam 102 follows a shared path withthe UF laser pulse beam 66 through the shared optics 50 and the patientinterface 52. In this way, the OCT sample portion beam 102 is generallyindicative of the location of the UF laser pulse beam 66. Similar to theUF laser beam, the OCT sample portion beam 102 passes through theZ-telescope 84, is redirected by the X-scan device 86 and by the Y-scandevice 88, passes through the objective lens assembly 94 and the patientinterface 52, and on into the eye 43. Reflections and scatter off ofstructures within the eye provide return beams that retrace back throughthe patient interface 52, back through the shared optics 50, backthrough the beam combiner 100, and back into the OCT light source anddetection device 98. The returning back reflections of the sampleportion 102 are combined with the returning reference portion 104 anddirected into the detector portion of the OCT light source and detectiondevice 98, which generates OCT signals in response to the combinedreturning beams. The generated OCT signals that are in turn interpretedby the control electronics to determine the spatial disposition of thestructures of interest in the patient's eye 43. The generated OCTsignals can also be interpreted by the control electronics to measurethe position and orientation of the patient interface 52, as well as todetermine whether there is liquid disposed between the posterior surfaceof the patient interface lens 96 and the patient's eye 43.

The OCT light source and detection device 98 works on the principle ofmeasuring differences in optical path length between the reference path106 and the sample path. Therefore, different settings of theZ-telescope 84 to change the focus of the UF laser beam do not impactthe length of the sample path for a axially stationary surface in theeye of patient interface volume because the optical path length does notchange as a function of different settings of the Z-telescope 84. Theranging subsystem 46 has an inherent Z range that is related to lightsource and the detection scheme, and in the case of frequency domaindetection the Z range is specifically related to the spectrometer, thewavelength, the bandwidth, and the length of the reference path 106. Inthe case of ranging subsystem 46 used in FIG. 3, the Z range isapproximately 4-5 mm in an aqueous environment. Extending this range toat least 20-25 mm involves the adjustment of the path length of thereference path 106 via a stage ZED within ranging subsystem 46. Passingthe OCT sample portion beam 102 through the Z-telescope 84, while notimpacting the sample path length, allows for optimization of the OCTsignal strength. This is accomplished by focusing the OCT sample portionbeam 102 onto the targeted structure. The focused beam both increasesthe return reflected or scattered signal that can be transmitted throughthe single mode fiber and increases the spatial resolution due to thereduced extent of the focused beam. The changing of the focus of thesample OCT beam can be accomplished independently of changing the pathlength of the reference path 106.

Because of the fundamental differences in how the sample portion 102(e.g., 810 nm to 850 nm wavelengths) and the UF laser pulse beam 66(e.g., 1020 nm to 1050 nm wavelengths) propagate through the sharedoptics 50 and the patient interface 52 due to influences such asimmersion index, refraction, and aberration, both chromatic andmonochromatic, care must be taken in analyzing the OCT signal withrespect to the UF laser pulse beam 66 focal location. A calibration orregistration procedure as a function of X, Y, and Z can be conducted inorder to match the OCT signal information to the UF laser pulse beamfocus location and also to the relative to absolute dimensionalquantities.

There are many suitable possibilities for the configuration of the OCTinterferometer. For example, alternative suitable configurations includetime and frequency domain approaches, single and dual beam methods,swept source, etc, are described in U.S. Pat. Nos. 5,748,898; 5,748,352;5,459,570; 6,111,645; and 6,053,613.

The system 2 can be set to locate the anterior and posterior surfaces ofthe lens capsule and cornea and ensure that the UF laser pulse beam 66will be focused on the lens capsule and cornea at all points of thedesired opening. Imaging modalities and techniques described herein,such as for example, Optical Coherence Tomography (OCT), and such asPurkinje imaging, Scheimpflug imaging, confocal or nonlinear opticalmicroscopy, fluorescence imaging, ultrasound, structured light, stereoimaging, or other known ophthalmic or medical imaging modalities and/orcombinations thereof may be used to determine the shape, geometry,perimeter, boundaries, and/or 3-dimensional location of the lens andlens capsule and cornea to provide greater precision to the laserfocusing methods, including 2D and 3D patterning. Laser focusing mayalso be accomplished using one or more methods including directobservation of an aiming beam, or other known ophthalmic or medicalimaging modalities and combinations thereof, such as but not limited tothose defined above.

Optical imaging of the cornea, anterior chamber and lens can beperformed using the same laser and/or the same scanner used to producethe patterns for cutting. Optical imaging can be used to provideinformation about the axial location and shape (and even thickness) ofthe anterior and posterior lens capsule, the boundaries of the cataractnucleus, as well as the depth of the anterior chamber and features ofthe cornea. This information may then be loaded into the laser 3-Dscanning system or used to generate a three dimensionalmodel/representation/image of the cornea, anterior chamber, and lens ofthe eye, and used to define the cutting patterns used in the surgicalprocedure.

Observation of an aim beam can also be used to assist in positioning thefocus point of the UF laser pulse beam 66. Additionally, an aim beamvisible to the unaided eye in lieu of the infrared OCT sample portionbeam 102 and the UF laser pulse beam 66 can be helpful with alignmentprovided the aim beam accurately represents the infrared beamparameters. The alignment guidance subsystem 48 is included in theassembly 62 shown in FIG. 3. An aim beam 108 is generated by an aim beamlight source 110, such as a laser diode in the 630-650 nm range.

Once the aim beam light source 110 generates the aim beam 108, the aimbeam 108 is transmitted along an aim path 112 to the shared optics 50,where it is redirected by a beam combiner 114. After being redirected bythe beam combiner 114, the aim beam 108 follows a shared path with theUF laser pulse beam 66 through the shared optics 50 and the patientinterface 52. In this way, the aim beam 108 is indicative of thelocation of the UF laser pulse beam 66. The aim beam 108 passes throughthe Z-telescope 84, is redirected by the X-scan device 86 and by theY-scan device 88, passes through the beam combiner 90, passes throughthe objective lens assembly 94 and the patient interface 52, and on intothe patient's eye 43.

The video subsystem 92 is operable to obtain images of the patientinterface and the patient's eye. The video subsystem 92 includes acamera 116, an illumination light source 118, and a beam combiner 120.The video subsystem 92 gathers images that can be used by the controlelectronics 54 for providing pattern centering about or within apredefined structure. The illumination light source 118 can be generallybroadband and incoherent. For example, the light source 118 can includemultiple LEDs. The wavelength of the illumination light source 118 ispreferably in the range of 700 nm to 750 nm, but can be anything that isaccommodated by the beam combiner 90, which combines the light from theillumination light source 118 with the beam path for the UF laser pulsebeam 66, the OCT sample beam 102, and the aim beam 108 (beam combiner 90reflects the video wavelengths while transmitting the OCT and UFwavelengths). The beam combiner 90 may partially transmit the aim beam108 wavelength so that the aim beam 108 can be visible to the camera116. An optional polarization element can be disposed in front of theillumination light source 118 and used to optimize signal. The optionalpolarization element can be, for example, a linear polarizer, a quarterwave plate, a half-wave plate or any combination. An additional optionalanalyzer can be placed in front of the camera. The polarizer analyzercombination can be crossed linear polarizers thereby eliminatingspecular reflections from unwanted surfaces such as the objective lenssurfaces while allowing passage of scattered light from targetedsurfaces such as the intended structures of the eye. The illuminationmay also be in a dark-filed configuration such that the illuminationsources are directed to the independent surfaces outside the capturenumerical aperture of the image portion of the video system.Alternatively the illumination may also be in a bright fieldconfiguration. In both the dark and bright field configurations, theillumination light source can be used as a fixation beam for thepatient. The illumination may also be used to illuminate the patient'spupil to enhance the pupil iris boundary to facilitate iris detectionand eye tracking. A false color image generated by the near infraredwavelength or a bandwidth thereof may be acceptable.

The assembly 62 of system 2 may comprise a fixation light 119 thatprovides visible light for the patient to fixate during measurement,alignment and treatment of the eye, for example. A lens 117 can beprovided to direct light to the eye 43 with vergence suitable forviewing the fixation light. Light emitted from lens 117 is reflectedwith beam splitter 121 along the optical path of the video camera andillumination optics.

The lens 117 may comprise a fixed lens or a variable lens, for example.The lens 117 may comprise a first configuration to provide a firstoptical vergence of the light entering the eye prior to placement offluid on the eye and a second vergence subsequent placement of theinterface fluid on the eye in order to correct for changes in refractionof the eye when fluid contacts the cornea. The first configuration maycomprise a substantially fixed vergence, or a variable vergence adjustedto the refractive properties of the eye, for example with a variablelens. For an emmetropic patient, the light entering the eye prior toplacement of the interface fluid can be collimated, for example. Thesecond configuration of lens 117 can provide a convergent light beam tothe eye to focus light onto the retina. As the cornea comprises about 40Diopters (hereinafter “D”) of optical power, and the interface fluid cansubstantially decrease the optical power of the eye, the lens 117 in thesecond configuration may provide about 40 D of positive optical power tofocus light onto the retina of the eye. This approximately 40D ofpositive vergence can be quite helpful with embodiments where thepatient is asked to fixate on the light when the patient interface fluidhas been placed on the cornea.

The illumination light from the illumination light source 118 istransmitted through the beam combiner 120 to the beam combiner 90. Fromthe beam combiner 90, the illumination light is directed towards thepatient's eye 43 through the objective lens assembly 94 and through thepatient interface 94. The illumination light reflected and scattered offof various structures of the eye 43 and patient interface travel backthrough the patient interface 94, back through the objective lensassembly 94, and back to the beam combiner 90. At the beam combiner 90,the returning light is directed back to the beam combiner 120 where thereturning light is redirected toward the camera 116. The beam combinercan be a cube, plate or pellicle element. It may also be in the form ofa spider mirror whereby the illumination transmits past the outer extentof the mirror while the image path reflects off the inner reflectingsurface of the mirror. Alternatively, the beam combiner could be in theform of a scraper mirror where the illumination is transmitted through ahole while the image path reflects off of the mirrors reflecting surfacethat lies outside the hole. The camera 116 can be a suitable imagingdevice, for example but not limited to, any silicon based detector arrayof the appropriately sized format. A video lens forms an image onto thecamera's detector array while optical elements provide polarizationcontrol and wavelength filtering respectively. An aperture or irisprovides control of imaging NA and therefore depth of focus and depth offield and resolution. A small aperture provides the advantage of largedepth of field that aids in the patient docking procedure.Alternatively, the illumination and camera paths can be switched.Furthermore, the aim light source 110 can be made to emit infrared lightthat would not be directly visible, but could be captured and displayedusing the video subsystem 92.

FIG. 3B shows a fixation light integrated into the fixed video opticalpath of laser system 2, in which assembly 62 is configured to illuminatethe eye with external illumination. The video camera to view the pupiland limbus of the eye may comprise a plurality of lenses to image theiris onto the sensor array of the camera. The plurality of lenses maycomprise first one or more lenses 111 and second one or more lenses 113.The beam splitter 121 can be located between the first lens and thesecond lens, for example. The beam splitter 121 may comprise a thinplate of optically transparent material, for example. The light emittedfrom the fixation light 119 is transmitted through lens 117 anddeflected along the substantially fixed video optical path. The eye 42can be illuminated with an external light source, for example a lightsource located away from axis 99 of the optical delivery system asdescribed herein.

FIG. 3C shows a mapped treatment region of the eye comprising the cornea43C, the lens 43L, the anterior lens capsule 43LAC, the posteriorcapsule 43LPC, and the limbus 43LI. The treatment region can be mappedwith computer modeling, for example ray tracing and phased based opticalmodeling to incorporate factors such as laser beam quality, pulse width,system transmission, numerical aperture, polarization, aberrationcorrection, and alignment. The treatment volume is shown extending alongthe Z-axis from the posterior surface of the optically transmissivestructure of the patient interface a distance of over 15 mm, such thatthe treatment volume includes the cornea, and the lens in which thetreatment volume of the lens includes the anterior capsule, theposterior capsule, the nucleus and the cortex. The treatment volumeextends laterally from the center of the cornea to beyond the limbus.The lateral dimensions of the volume are defined by a Y contour anteriorto the limbus and by an X contour posterior to the limbus. The treatmentvolume shown can be determined by a person of ordinary skill in the artbased on the teachings described herein. The lateral positions ofpredicted optical breakdown for ZL fixed to 30 mm and ZL fixed to 20 mmare shown. These surfaces that extend transverse to the axis 99 alongthe Z-dimension correspond to locations of optical scanning of the X andY galvos to provide optical breakdown at lateral locations away from theaxis 99. The curved non-planner shape of the scan path of opticalbreakdown for ZL-30 mm and ZL-20 mm can be corrected with the mappingand look up tables as described herein. The curved shape of the focuscan be referred to as a warping of the optical breakdown depth and thelook up tables can be warped oppositely or otherwise adjusted so as tocompensate for the warping of the treatment depth, for example.Additionally, the warping inherent in the prediction from the model canbe incorporated in the generic look-up table and any further error fromthis predicted form as indicated by measurement and application of acorrection factor to offset this error may also be called a warping ofthe look up table.

The treatment region is shown for setting the laser beam energy aboutfour times the threshold amount for optical breakdown empiricallydetermined for a beam near the limbus of the system. The increasedenergy or margin above ensures that the beam system will be able totreat given variability in contributing factors. Theses contributingfactors may include degradation over lifetime of the laser with regardto energy, beam quality, transmission of the system, and alignment.

The placement of the posterior surface of the optically transmissivestructure of the patient interface away from the surface of the corneacan provide the extended treatment range as shown, and in manyembodiments the optically transmissive structure comprises the lens. Inalternative embodiments, the posterior surface of the opticallytransmissive structure can be placed on the cornea, for example, and themapping and look up tables as described herein can be used to providethe patient treatment with improved accuracy.

The optically transmissive structure of the patient interface maycomprise one or more of many known optically transmissive materials usedto manufactures lenses, plates and wedges, for example one or more ofglass, BK-7, plastic, acrylic, silica or fused silica for example.

The computer mapping of the treatment volume may optionally be adjustedwith mapping based on measurements of a constructed system as describedherein.

FIG. 4A shows correspondence among movable and sensor components of thelaser delivery system 2. The movable components may comprise one or morecomponents of the laser delivery system 2 as described herein. Themovable components of the laser delivery system may comprise the zoomlens capable of moving distance ZL, the X galvo mirror 96 capable ofmoving an angular amount Xm, and the Y galvo mirror 88 capable of movingan angular amount Ym. The movable components of the OCT system maycomprise the movable OCT reference arm configured to move the referencepath 106 a distance ZED. The sensor components of the laser system maycomprise the video camera having X and Y pixels, Pix X and Pix Y,respectively, and sensor components of the OCT system such as thespectral domain detection as described herein. The patient support whichmay comprise a bed is movable in three dimensions so as to align the eye43 of the patient P with laser system 2 and axis 99 of the system. Thepatient interface assembly comprises an optically transmissive structurewhich may comprise an interface lens 96, for example, configured to bealigned with system 2 and an axis of eye 43. The patient interface lenscan be placed on the patient eye 43 for surgery, and the opticallytransmissive structure can be placed at a distance 162 from theobjective lens 94. In many embodiments, the optically transmissivestructure comprises lens 96 placed a contact lens optical distance 162(hereinafter “CLopt”). The optically transmissive structure comprises athickness 164, and the thickness 164 may comprise a thickness of thecontact lens 96, for example. Although the optically transmissivestructure comprising contact lens 96 may contact the eye 2, in manyembodiments the contact lens 168 is separated from the cornea with gap168 extending between the lens and the vertex of the cornea, such thatthe posterior surface of the contact lens 168 contacts a solutioncomprising saline or a viscoelastic solution, for example.

FIG. 4B shows mapping of coordinate references from an eye spacecoordinate reference system 150 to a machine coordinate reference system151 so as to coordinate the machine components with the physicallocations of the eye. The laser system 2 can map physical coordinates ofthe eye 43 to machine coordinates of the components as described herein.The eye space coordinate reference system 150 comprises a first Xdimension 152, for example an X axis, a second Y dimension 154, forexample a Y axis, and a third Z dimension 156, for example a Z axis, andthe coordinate reference system of the eye may comprise one or more ofmany known coordinate systems such as polar, cylindrical or Cartesian,for example. In many embodiments the reference system 150 comprises aright handed triple with the X axis oriented in a nasal temporaldirection on the patient, the Y axis oriented superiorly on the patientand the Z axis oriented posteriorly on the patient. In many embodiments,the corresponding machine coordinate reference system 151 comprises afirst X′ dimension 153, a second Y′ dimension 155; and a third Z′dimension 157 generally corresponding to machine actuators, and thecoordinate reference system of the machine may comprise one or more ofmany known coordinate systems such as polar, cylindrical or Cartesian,and combinations thereof, for example.

The machine coordinate reference 151 may correspond to locations of oneor more components of system 2. The machine coordinate reference system151 may comprise a plurality of machine coordinate reference systems.The plurality of machine coordinate reference systems may comprise acoordinate reference system for each subsystem, for example. Forexample, dimension 157 may correspond to movement of the z-telescopelens capable of moving distance ZL. The dimension 153 may correspond tomovement of the X galvo mirror 86 capable of moving an angular amountXm, and the dimension 153 may correspond to movement of the Y galvomirror 88 capable of moving an angular amount Ym. Alternatively or incombination, the dimension 157 may correspond to movable OCT referencearm configured to move the reference path 106 a distance ZED, along withdimension 157 corresponding to a movement of the z-telescope for the OCTbeam, and the dimension 153 and the dimension 155 may correspond tomovement of the X galvo mirror 86 and the Y galvo mirror 88,respectively, for the OCT beam. The dimension 151 may correspond to Xpixels of the video camera and dimension 153 may correspond to Y pixelsof the video camera. The axes of the machine coordinate reference systemmay be combined in one or more of many ways, for example the OCTreference arm movement of the reference path 106 the distance ZED can becombined with movement of the z-telescope lens capable of moving thedistance ZL, for example. In many embodiments, the locations of thecomponents of the laser system 2 are combined when in order to map theplurality of machine coordinate reference systems to the coordinatereference system 150 of eye 43.

In many embodiments, the eye coordinate reference system is mapped froman optical path length coordinate system to physical coordinates of theeye based on the index of refraction of the tissues of the eye. Anexample is the OCT ranging system where measurements are based onoptical thicknesses. The physical distance can be obtained by dividingthe optical path length by the index of refraction of the materialthrough which the light beam passes. Preferable the group refractiveindex is used and takes into account the group velocity of the lightwith a center wavelength and bandwidth and dispersion characteristics ofthe beam train. When the beam has passed through more than one material,the physical distance can be determined based on the optical path lengththrough each material, for example. The tissue structures of the eye andcorresponding index of refraction can be identified and the physicallocations of the tissue structures along the optical path determinedbased on the optical path length and the indices of refraction. When theoptical path length extends along more than one tissue, the optical pathlength for each tissue can be determined and divided by thecorresponding index of refraction so as to determine the physicaldistance through each tissue, and the distances along the optical pathcan be combined, for example with addition, so as to determine thephysical location of a tissue structure along the optical path length.Additionally, optical train characteristics may be taken into account.As the OCT beam is scanned in the X and Y directions and departure fromthe telecentric condition occurs due to the axial location of the galvomirrors, a distortion of the optical path length is realized. This iscommonly known as fan error and can be corrected for either throughmodeling or measurement.

As one or more optical components and light sources as described hereinmay have different path lengths, wavelengths, and spectral bandwidths,in many embodiments the group index of refraction used depends on thematerial and the wavelength and spectral bandwidth of the light beam. Inmany embodiments, the index of refraction along the optical path maychange with material. For example, the saline solution may comprise afirst index of refraction, the cornea may comprise a second index ofrefraction, the anterior chamber of the eye may comprise a third indexof refraction, and the eye may comprise gradient index lens having aplurality of indices of refraction. While optical path length throughthese materials is governed by the group index of refraction, refractionor bending of the beam is governed by the phase index of the material.Both the phase and group index can be taken into account to accuratelydetermine the X, Y, and Z location of a structure. While the index ofrefraction of tissue such as eye 43 can vary with wavelength asdescribed herein, approximate values include: aqueous humor 1.33; cornea1.38; vitreous humor 1.34; and lens 1.36 to 1.41, in which the index ofthe lens can differ for the capsule, the cortex and the nucleus, forexample. The phase index of refraction of water and saline can be about1.325 for the ultrafast laser at 1030 nm and about 1.328 for the OCTsystem at 830 nm. The group refractive index of 1.339 differs on theorder of 1% for the OCT beam wavelength and spectral bandwidth. A personof ordinary skill in the art can determine the indices of refraction andgroup indices of refraction of the tissues of the eye for thewavelengths of the measurement and treatment systems as describedherein. The index of refraction of the other components of the systemcan be readily determined by a person of ordinary skill in the art basedon the teachings described herein.

FIG. 5A shows a flow chart of a method 500 for providing accurate anddistortion-free corneal topography measurement and subsequentintegration with the laser treatment, in accordance with embodiments.The method 500 comprises the following main steps. In a step 525, thepatient's eye is positioned within the capture range of the measurementsystem of the laser eye surgery system 2 or 2A described herein. In astep 550, the measurement system is used to measure corneal shape withhigh accuracy. Such a measurement system may comprise the rangingsubsystem 46 described above. In a step 575, any changes in the patienteye orientation that may occur between the measurement time and thelaser treatment time is accounted for.

Positioning step 525: In the step 525, the patient's eye is positionedwithin the capture range of the measurement system of the laser eyesurgery system as described herein, such as shown in FIGS. 2 and 3A, forexample. Positioning of the patient for laser surgery is typicallyenabled by motion of the patient bed 34 or by motion of the laser system2. Typically, the operator has manual control of the lateral and axialposition, guiding the docking mechanism or patient interface 52 intoplace in a step 528. In the absence of a docking mechanism, an operatormeans for guiding the motion so that the eye, and specifically thecornea, is placed within the operative range of the measurement systemmay be provided. This can be accomplished with the use of subsystems ofthe laser system 2 or 2 a described herein such as alignment guidancesystem 48 of laser system 2 or imaging subsystem 546 of laser system 2a. Initial patient position can be guided by a video camera, guiding theeye into lateral position by centering the video image, and into axialposition by focusing the image. At this point, the cornea is placedwithin the capture range of the OCT system of the ranging subsystem 46or imaging subsystem 546, typically X mm to Y mm axially, in a step 531.The OCT system can be used to measure the axial position of the corneain a step 534, and a suitable display provides the operator guidance forfinal, accurate positioning. Alternatively, a visual imaging system suchas a camera, a camera coupled to a microscope which may share opticswith the laser system 2 or 2 a, a CCD, among others may be used insteadof the OCT system to facilitate the positioning step 525.

Since the video and OCT systems are typically configured to operate withthe docking system, which often has additional optical elements andliquid medium in the optics path, the focusing algorithms of the lasersystem may be adjusted to account for operation without the dockingmechanism optics and interface medium.

Measurement step 550: In the step 550, the measurement system is used tomeasure corneal shape with high accuracy. The laser system 2 or 2Acomprises a subsystem for mapping the ocular surfaces that are beingtreated such as the ranging subsystem 46 having an OCT system describedherein or the imaging subsystem 546. As described below, the imagingsubsystem 546 may apply other modalities for mapping the ocular surfacessuch as Placido imaging, Hartmann-shack wavefront sensing, confocaltomography, low coherence reflectometry, among others. The measurementstep 550 can be performed once the eye is positioned correctly in thestep 525 above. A fixation light can optionally be introduced to helpthe patient keep the eye pointed at a fixed angle. If the measurementdata capture is sufficiently fast, for example, on the order of onesecond, a fixation light may not be necessary. In a step 553 ofmeasurement 550, multiple OCT or other scans of the cornea surfaces canbe acquired in a short time. Multiple scans can increase the confidenceof obtaining good data. In a step 556, post-processing of the scans canremove potential eye motion and further improve the measurementaccuracy. In a step 562 of measurement step 550, corneal power can bemeasured from camera images of reflected light from the cornea.

Once the cornea surfaces have been mapped, polynomial, or other fittingalgorithms can be used to calculate commonly used parameters of thecornea in a step 559. Commonly used parameters include the optical powerof the cornea, astigmatic axis angle, and astigmatism magnitude.

Coordinate system transfer step 575: In the step 575, any changes in thepatient eye orientation that may occur between the measurement time andthe laser treatment time is accounted for. Often times, it is probablethat when the patient eye is docked for treatment such as with thesuction ring of the patient interface 52, the eye, including its variousanatomical features, will change its position relative to the lasersystem coordinates. This change can be a result of patient headmovement, eye movement, or because of force applied during docking. Insome cases, the refractive properties of the air or any liquid over theeye can distort the images of the eye. For example, the suction ring ofthe patient interface 52 may be filled with one or more of a solution,saline, or a viscoelastic fluid. It can be helpful to transform thecorneal measurements, like the astigmatic axis angle, to a newcoordinate system to account for any movement and distortion. Severalmeans for accomplishing this are provided.

In some embodiments, the operator can mark the patient eye prior to themeasurement with ink dots that are typically positioned diametricallyacross on the periphery of the cornea in a step 578. These dots can beacquired by the imaging camera after docking for treatment and used forcalculating the coordinate transformation in a step 581.

In other embodiments, ocular features that are visible in the videoimages, or the OCT or other scans, taken during the measurement step areused. These features are correlated to the images taken after dockingfor treatment in a step 584. This correlation can be done by digitalimage processing algorithms, or manually by the operator. When donemanually, the operator is presented by overlapped images (measurementand treatment steps) on the control screen, and the images are manuallymanipulated in translation and rotation until they are visibly matched.The image manipulation data can be detected by the display software andused for the coordinate transform.

Although the above steps show method 500 of providing accurate anddistortion-free corneal topography measurement and subsequentintegration with the laser treatment in accordance with manyembodiments, a person of ordinary skill in the art will recognize manyvariations based on the teaching described herein. The steps may becompleted in a different order. Steps may be added or deleted. Forexample, the shape of the cornea may be measures before, during, orafter docking for treatment such as with a suction ring of the patientinterface 52. Many of the steps may be repeated as often as beneficialto the method.

One or more of the steps of the method 500 may be performed with thecircuitry as described herein, for example, one or more the processor orlogic circuitry such as the programmable array logic for fieldprogrammable gate arrays. The circuitry may be programmed to provide oneor more of the steps of method 500, and the program may comprise programinstructions stored on a computer readable memory or programmed steps ofthe logic circuitry such as the programmable array logic or the fieldprogrammable gate array, for example.

FIG. 5B shows a laser eye surgery 2A similar to system 2 of FIG. 2 inaccordance with embodiments. The laser eye surgery system 2 is similarto the laser eye surgery system 2 as described herein and comprises manyof the same components. In particular, the laser eye surgery system 2Acomprises an imaging subsystem 646 which may be used to visualize andimage the eye 43, and the control panel/GUI 56 comprises a display 56A.The laser eye surgery system 2A may be configured to couple to aseparate and distinct ancillary diagnostic system 648. For the laser eyesurgery system 2, the OCT system of the ranging subsystem 46 may be usedto position the patient eye in the step 525 and/or to measure the shapeof the cornea in the step 550. For the laser eye surgery system 2A, theancillary diagnostic system 648 is used to measure the shape of thecornea in the step 550. The ancillary diagnostic system 648 may applyany number of modalities to measure the shape of the eye including oneor more of a keratometry reading of the eye, a corneal topography of theeye, an optical coherence tomography of the eye, a Placido disctopography of the eye, a reflection of a plurality of points from thecornea topography of the eye, a grid reflected from the cornea of theeye topography, a Hartmann-Shack topography of the eye, a Scheimpflugimage topography of the eye, a confocal tomography of the eye, or a lowcoherence reflectometry of the eye. The shape of the cornea can bemeasured before, during, or after the patient interface 52 is dockedwith the eye of the patient. The shape of the cornea may be measuredusing the ancillary diagnostic system 648 while the ancillary diagnosticsystem 648 is separate from the laser eye surgery system 2A, such as bybeing in a different room. Images captured by the ranging subsystem 46of the laser eye surgery system 2 or the imaging subsystem 546 of thelaser eye surgery system 2A and the ancillary diagnostic system 548 maybe displayed with a display of the control panel/GUI 56 of the laser eyesurgery system 2 or the display 56A of the laser eye surgery system 2A,respectively. The control panel/GUI 56 may also be used to modify,distort, or transform any of the displayed images.

FIGS. 6A to 6C show images of the eye which may be displayed for examplein the display 56A of the laser eye surgery system 2A or the display ofthe laser eye surgery system 2, for example. The images shown illustratedistortion which may occur and the distortion may not be to scale and isprovided for illustration purposes in accordance with embodiments.

FIG. 6A shows a coordinate system 600A overlaid on an image 601A of aneye EY. The image 601A of the eye 43 shows various anatomical featuresincluding the sclera 43SC, the limbus 43LI, the iris 43I, and the pupil43PU. Similar images and biometric information can be obtained withsimilar maps. In many embodiments, this image 601A can be captured bythe imaging subsystem 546 of the laser eye surgery system 2A. The image601A is captured prior to coupling the eye with a suction ring of thepatient interface 52 of the laser eye surgery system 2. The image 601Amay most accurately represent the positions of the various tissuestructures of the eye 43. The image 601A may comprise one or more ofmany images or measurements as described herein. A person of ordinaryskill in the art will recognize that the pupil seen through thecornea/air interface comprises a virtual pupil of the eye. Although theshape and optical power of the cornea may provide distortion andmagnification of the pupil and iris, a person of ordinary skill in theart can correct this distortion and magnification based on the teachingdescribed herein and in accordance with embodiments as appropriate. Forexample, the virtual image of the pupil can be transformed to an eyespace coordinate system 150 as described herein.

The structures shown in coordinate system 600A can be transformed to thecoordinate reference system 150 of eye 2 in one or more of many ways.For example, the tissue structures shown in the image such as the limbusand the iris can be identified, and the transform to the eye coordinatereference system 150 determined based on the location of the tissuestructure and depth and location in relation to correspondence opticaltissue surfaces such as the surface of the cornea. The locations of thetissue structures identified in the image 601 can be determined andmapped to eye coordinate reference system 150 or to one or morecoordinate reference systems as described herein.

In many embodiments, iris registration is used to determine acyclotorsional angle of the eye. A first image of the iris can beobtained with a first camera prior to the patient interface contactingthe eye, and a second image of the iris can be obtained when the patientinterface contacts the eye. The first camera image of the iris can beregistered with the second camera image of the iris of the patient inorder to determine the cyclo torsional angle of the eye as describedherein. In many embodiments, the first non-contact image of the eyecomprises an image of the iris wherein the cornea of the eye magnifiesand may distort the virtual image of the iris seen with the camera, andthe second contact image of the eye comprises an image of the eyemeasured when the patient interface contacts the eye. The first imageand the second image can be registered in one or more of many ways, andthe processor can be configured with instructions to determine thecyclotorsional angle of the eye with instructions of an algorithm suchas one or more of an image matching algorithm or a pattern recognitionalgorithm, for example. The processor comprising the instructions of thealgorithm can be configured to identify a pattern of the first image inrelation to an axis of the eye as described herein and to identify thelocation of the pattern in the second image in order to determine thecyclotorsional angle of the eye, for example.

In many embodiments, ray tracing through the full thickness cornealprofile map can be used to correct distortions of the cornea, such asone or more of distortions of the anterior corneal surface of theposterior corneal surface. For example, when the eye has been docked andthe fluid of the patient interface contacts the eye, distortions of theposterior surface of the eye can influence light rays travelling throughthe cornea, and distortions of images of tissue structure posterior tothe posterior surface of the cornea can be corrected in response to raytracing. The ray tracing can be performed by a person of ordinary skillin the art using Snell's law and the index of refraction of the corneaand contacting material such as air, interface fluid, or aqueous humor,for example. Alternatively or in combination, distortions of theanterior corneal surface and the corresponding distortion of imagesmeasured through the cornea can be corrected with ray tracing, forexample when the cornea is exposed to air. While distortions of theanterior corneal surface can be corrected in a manner similar to theposterior surface with ray tracing, work in relation to embodimentssuggests that coupling the eye to the patient interface with a fluidcontacting the patient interface and having an index of refractionsimilar to the cornea can decrease the affect of distortions of theanterior corneal surface. Based on the teachings disclosed herein, aperson of ordinary skill in the art can determine and correct fordistortions of images of the eye related to corneal distortions with raytracing and corneal profile maps as described herein, for example.

In many embodiments one or more of the first image or the second imageis adjusted in response to distortion of the one or more of the firstimage or the second image. The distortion can be related to the index ofrefraction viscous fluid into the patient interface that affects theoptical properties of the image of the eye, or the distortion of theoptical delivery system, and combinations thereof. In many embodiments,the distortion of the cornea can be determined in response to athickness profile of the cornea, and aberrations of the image introducedby the thickness profile of the cornea corrected.

FIG. 6A1 shows corneal profile data 610A of cornea 43C for thecoordinate system and image of FIG. 6A. The corneal profile data 610Acomprises a plurality of corneal profiles from the tomography systemtaken with the patient interface away from the eye as in FIG. 6A. Theplurality of corneal profiles comprises a first corneal profile 612A, asecond corneal profile 614A and a third corneal profile 616A. Additionalcorneal profiles can be taken. The cornea profiles can be obtained withtomography scans along a plane for example, and detection of the cornealsurface. The corneal surface can be fit as described herein, for examplewith polynomials as described herein. The fit corneal surface can beused to determine the corneal topography and treatment parameters asdescribed herein. The corneal profile data may comprise coordinatesystem 600A, for example.

FIG. 6B shows a distorted coordinate system 600B overlaid on the eyeimage 601B of the eye 43. The image 601A of the eye 43 shows variousanatomical features including the sclera 43SC, the limbus 43LI, the iris43I, and the pupil 43PU. In many embodiments, this image 601B is takenof the eye by a visual imaging system of the laser eye surgery system 2.This image 601B is taken when the anterior surface of the eye 43 iscoupled with a suction ring of the laser eye surgery system 2 to exposethe anterior surface to air. The suction ring may distort the tissuestructures of the eye 43 when placed thereon. The locations of thevarious tissue structures of the eye, such as one or more structures ofthe iris, in relation to the distorted coordinate system 600B can bemapped to their respective locations the coordinate system 600A in image601A to account for this distortion.

FIG. 6C shows a distorted coordinate system 600C overlaid on the eyeimage 601C of the eye 43. The image 601C of the eye 43 shows variousanatomical features including the sclera 43SC, the limbus 43LI, the iris43I, and the pupil 43PU. In many embodiments, this image 601C is takenof the eye by a visual imaging system of the laser eye surgery system 2.This image 601C is taken when the anterior surface of the eye 43 iscoupled with a suction ring of the laser eye surgery system 2 and thesuction ring is filled with a liquid such as saline or viscoelasticsubstance. In addition to distortion from interfacing with the suctionring, the refractive properties of the liquid may also distort lightreflecting back from the anterior surface of the eye EY. The locationsof the various tissue structures of the eye, such as one or morestructures of the iris, in relation to the distorted coordinate system600C can be mapped to their respective locations the coordinate system600A in image 601A to account for these distortions. Alternatively or incombination, the structures can be mapped to eye coordinate referencesystem 150

FIG. 6C1 shows corneal profile data 610C of cornea CO for the coordinatesystem and image of FIG. 6C. The corneal profile data 610C can beprovided with mapping of the corneal profile data 610A, or based on asecond set of similar measurements. The corneal profile data 610Ccomprises a plurality of corneal profiles from the tomography systemtaken with the patient interface away from the eye as in FIG. 6A. Theplurality of corneal profiles comprises a first corneal profile 612C, asecond corneal profile 614C and a third corneal profile 616C. Additionalcorneal profiles can be taken. The cornea profiles can be obtained withtomography scans along a plane for example, and detection of the cornealsurface. The corneal surface can be fit as described herein, for examplewith polynomials as described herein. The corneal profile data 610C maya coordinate system 600C overlaid. The corneal profile data 610C ofcoordinate system 600C may be mapped to eye coordinate reference 150 asdescribed herein, for example. Alternatively or in combination, thecorneal profile data 610C may comprise eye coordinate reference 150 asdescribed herein, for example when the treatment is mapped based on thepatient interface coupled to the eye.

In many embodiments, the non-distorted image 601A is modified to providea distorted first image with a distortion similar to that in images 601Bor 601C. The distorted image 601A may then be displayed on the display56A or other display of the laser eye surgery system 2 or 2A. A user ofthe laser eye surgery system 2 or 2A can adjust one or more of alocation or an angle of the distorted image 601A on the display 56A orother display. Locations of a plurality of laser beam pulses from thecutting laser subsystem 44 can then be adjusted in response to thelocation or the angle of the first distorted image 601A on the display56A or other display. In some embodiments, the distorted first image601A is overlaid on the distorted image 601B or 601C on the display 56Aor other display to determine the position and the angle of the eye fortreatment. A processor of the laser eye surgery system 2 or 2A candetermine the position and the angle of the distorted first image 601Aon the display in response to user input to adjust the locations of theplurality of laser beam pulses from the cutting laser subsystem 44.

FIG. 6A2 shows corneal thickness profile data for the coordinate systemand images of FIGS. 6A and 6A1. The corneal profile data 610A comprisesa plurality of corneal thickness profiles from the tomography systemtaken with the patient interface away from the eye as in FIG. 6A. Theplurality of corneal profiles comprises a first corneal thicknessprofile 617A, a second corneal thickness profile 618A and a thirdcorneal profile 619A. Additional corneal profiles can be taken.

Each of the thickness profiles may comprise a difference between ananterior surface profile and a posterior surface profile, for example.The first corneal thickness profile 617A may comprise a differencebetween a first anterior surface profile 612A and a first posteriorsurface profile 611A. The second corneal thickness profile 618A maycomprise a difference between second anterior surface profile 614A and asecond posterior surface profile 613A. A third corneal profile 619A maycomprise a difference between third anterior surface profile 616A and athird posterior surface profile 615A. Additional corneal profiles can betaken.

Each of the corneal thickness profiles coordinate system 600AC of can bemapped to the physical eye coordinate reference system 150.

FIG. 6C2 shows corneal thickness profile data for the coordinate systemand images of FIGS. 6C and 6C1. The corneal thickness profile data 610Acomprises a plurality of corneal thickness profiles from the tomographysystem taken with the patient interface away from the eye as in FIG. 6C.The plurality of corneal profiles comprises a first corneal thicknessprofile 617C, a second corneal thickness profile 618C and a thirdcorneal profile 619C. Additional corneal profiles can be taken.

Each of the thickness profiles may comprise a difference between ananterior surface profile and a posterior surface profile, for example.The first corneal thickness profile 617C may comprise a differencebetween a first anterior surface profile 612C and a first posteriorsurface profile 611C. The second corneal thickness profile 618C maycomprise a difference between second anterior surface profile 614C and asecond posterior surface profile 613C. A third corneal profile 619C maycomprise a difference between third anterior surface profile 616C and athird posterior surface profile 615C. Additional corneal profiles can betaken.

Each of the corneal thickness profiles coordinate system 600C of can bemapped to the physical eye coordinate reference system 150.

FIG. 6A3 shows a corneal thickness profile map 620A for the coordinatesystem and images of FIGS. 6A, 6A1 and 6A2. The thickness profile mapgenerally comprises a representation of three dimensional thicknessprofile data of the cornea, and may comprise three dimensional thicknessdata of the cornea. For example, the thickness profile data may comprisea two dimensional array in which the thickness of the cornea is storedfor each two dimensional location of the array.

The corneal thickness profile map 620 can be determined based on thefirst corneal thickness profile 617A, the second corneal thicknessprofile 618A and the third corneal thickness profile 619A, for example.The corneal thickness profile map 620A can be shown in relation to thepupil 43PU and the limbus 43LI. The corneal thickness profile map 620Acan be displayed to the user in one or more of many known formats suchas with color coding of thicknesses or with equal depth contour lines.The equal depth contour lines may comprise a first equal depth contourline 622A, a second equal depth contour line 624A. The corneal thicknessprofile data can be fit as described herein, for example with apolynomial as described herein, in order to provide the cornealthickness profile map 620. The maps can be obtained with reference tocoordinate system 600A and mapped to eye coordinate reference system150, for example.

FIG. 6C3 shows a corneal thickness profile map 620C for the coordinatesystem and images of FIGS. 6C, 6C1 and 6C2. The corneal thicknessprofile map 620C can be determined based on the first corneal thicknessprofile 617C, the second corneal thickness profile 618C and the thirdcorneal thickness profile 619C, for example. The corneal thicknessprofile map 620C can be shown in relation to the pupil 43PU and thelimbus 43LI. The corneal thickness profile map 620C can be displayed tothe user in one or more of many known formats such as with color codingof thicknesses or with equal depth contour lines. The equal depthcontour lines may comprise a first equal depth contour line 622C, asecond equal depth contour line 624C. The corneal thickness profile datacan be fit as described herein, for example with a polynomial asdescribed herein, in order to provide the corneal thickness profile map620. The maps can be obtained with reference to coordinate system 600Cand mapped to eye coordinate reference system 150, for example.

Work in relation to embodiments of the present disclosure suggest thatthe corneal thickness profile maps and data as disclosed herein areresistant to mechanical deformation when the suction ring is placed onthe eye, and can be used to align the eye about the cyclotorsion alaxis, for example. The corneal thickness profile maps can beparticularly well suited to align eyes having prior refractive surgery,such as eyes that have received LASIK or PRK or other refractivesurgery, for example.

FIGS. 7A and 7B show side views of a plurality of axes of the eye 43when the eye views a fixation target and the eye is measured with animaging system 646 prior to contacting a patient interface. The imagingsystem 646 can be used to measure one or more optical structures of theeye, and the processor of the laser system can be used to determinelocations of the incisions in response to locations of the one or moreoptical structures. The imaging system 646 may comprise one or morecomponents of the ranging system 46 as described herein alignment andmay comprise one or more components of guidance system 48 as describedherein, for example the OCT system of ranging system 46 and video cameraof alignment guidance system 48. Alternatively or in combination, theimaging system 646 may comprise one or more components of separatediagnostic system 648 as described herein. The imaging system 646 may bylocated on laser system 2, or may comprise separate and distinctancillary diagnostic system 648, and combinations thereof, for example.

Imaging system 646 can be aligned with one or more axes of the eye asdescribed herein, for example with the patient viewing the fixationlight 119. In many embodiments, the patient views fixation light 119,and the imaging system 646 is aligned with the eye in one or more ofmany ways as described herein.

Imaging system 648 comprises fixation light 119 as described herein forthe patient to view when measurements are obtained. The fixation light119 allows the patient to fixate in order to align the axes of thecoordinate system 150 of the eye with one or more reference axes of thecoordinate system 650 of imaging system 646. The imaging system may 648comprise a measurement axis 699 that extends along an optical axis ofthe measurement system, and the fixation light 119 can be located alongthe measurement axis 699 to align the eye with the measurement system.The measurement axis 699 may comprise axis 99 of the optical deliverysystem of laser system 2 when laser system 2 is used for measurements ofthe eye prior to contacting the eye with the patient interface. Theinitial measurement reference coordinate system 650 of imaging system646 comprises a first dimension 652, a second dimension 654 and a thirddimension 646, for example. The dimensions of the coordinate system 650may comprise a right handed triple orthogonal coordinate referencesystem, for example. The third dimension 646 may comprise themeasurement axis 699 of the measurement system, for example. For initialmeasurements of the eye prior to the patient interface contacting theeye, the coordinate reference system may comprise the eye coordinatereference system 150 as described herein. When the eye has beencontacted with the patient interface, the eye coordinate referencesystem 150 for treatment with the laser can be one or more of rotate ortranslated with respect to the initial measurement reference coordinatesystem 650.

The imaging system 646 includes sensors to image one or more tissuestructures of the eye and can be used to determine one or more axes ofthe eye as described herein. The imaging system 646 can image andprofile one or more structures of the eye as described herein, such asone or more of the cornea of the eye 43C, the anterior surface of thecornea, the posterior surface of the cornea, the iris of the eye 43I,the pupil of the eye 43PU, the natural pupil of the eye 43PUN, the lensof the eye 43L, the anterior capsule of the lens 43LAC, the posteriorcapsule of the lens 43LPC, the entrance pupil of the eye 43ENP, thenatural entrance pupil of the eye, the vertex of the cornea 43VX. Inmany embodiments, tomography of the cornea is combined with surfacetopography of the cornea and the video camera images of the cornea todetermine one or more axes of the eye 43.

The vertex 43VX of the cornea may comprise a central part of the cornealocated along the optical axis 43AO of the eye that extendssubstantially perpendicular to the plane of the eye, and may comprise acenter of the cornea as determined in response to a measurement of thelimbus extending around the perimeter of the cornea.

The imaging system 646 can be used to determine one or more opticalstructures of the eye when the eye fixates naturally without contactingthe patient interface in order to determine locations of the one or moreoptical structures of the eye when the eye contacts the patientinterface. In many embodiments, the imaging system 646 is used todetermine one or more of the optical axis of the eye 43AO, the center ofcurvature of the anterior corneal surface, the center of curvature ofthe posterior corneal surface, the center of curvature of the lenscapsule anterior surface, or the center of curvature of lens capsuleposterior surface. The optical axis of the eye may comprise a straightline extending from the center of curvature of the anterior surface ofthe cornea to the center of curvature of the posterior surface of theposterior lens capsule. In many embodiments, the centers of curvaturemay not lie on a straight line, and the processor of the laser eyesurgery system can be used to determine the optical axis 43AO with anorientation and location that decreases the distance from the opticalaxis to each of the center of curvature of the cornea anterior surface,the center of curvature of the cornea posterior surface, the center ofcurvature of the lens capsule anterior surface, and center of curvatureof the capsule posterior surface, for example, with least squaresfitting of the optical axis to the centers of curvature for example.

The curvatures and the centers of curvature of the eye can be used todetermine the locations of the cardinal points of the eye comprising theobject point where the fixation light 119 is located, the image pointwhere the center of the fovea 43FV is located when the patient views thefixation light, the anterior nodal point 43NA of the eye, the posteriornodal point 43NP, the anterior principal point 43AP, and the posteriorprincipal point 43PP. One or more of these cardinal points of the eyecan be used to determine incision locations of the pulsed laser beam,and these cardinal points and the corresponding axes can be shown on adisplay to a user to determine locations on the incisions, in accordancewith many embodiments.

One or more of the natural entrance pupil 43ENP or the natural exitpupil 43EXP of the eye can be determined and may be used to determinelocations of the incisions with the pulsed laser beam. The entrancepupil 43ENP of the eye comprises a virtual image of the pupil of the eyeas seen by light rays entering the eye from the fixation light 119. Thenatural exit pupil of the eye 43EXP may comprise the image of the iris43I formed by lens 43I as seen from the fovea.

Referring to FIG. 7B, the cardinal points of the eye and image formingaxes of the eye are shown in detail. The iris 43I can be seen inrelation to the physical pupil center 43PC, the location of the centerof the entrance pupil 43ENP along the optical axis 43AO, and thelocation of the center of the exit pupil 43EXP along the optical axis43AO. The visual axis 43VA is shown extending from the fixation light tothe anterior node 43NA, and from the posterior node 43NP to the centerof the fovea, with the first and anterior node separated from the secondand posterior node along the optical axis 43AO. The line of sight 43 LOScan be seen extending from the fixation light 119 to the center of theentrance pupil 43ENP, and from the center of the exit pupil 43EXP to thecenter of the fovea, with the center of the entrance pupil and thecenter of the exit pupil located along the optical axis.

The axes of the eye that can be identified and determined with theimaging system 646 or the processor of laser system (and combinationsthereof) include a fixation axis 43FA, a visual axis 43VA, a line ofsight 43LOS, a pupillary axis 43PA and an optical axis 43AO.

The 43FA fixation axis of the eye may comprise an axis extending fromthe fixation light 119 through a center of rotation of the eye 43C.

The line of sight 43LOS may comprise a straight line extending from thefixation light through the center of the entrance pupil 43EP when thepatient views the fixation light. The line of sight 43LOS may alsocomprise a straight line extending from the fovea to the exit pupil ofthe eye when the patient views the fixation light. The entrance pupil Pcomprises a virtual image of the pupil that the light rays from thefixation light entering the eye are directed toward, and can be imagedwith the video camera of the alignment assembly 48 as described herein.The exit pupil 43EXP comprises

The pupillary axis 43PA may comprise a line perpendicular to the surfaceof the cornea, passing through the center of the pupil, for example.

The visual axis of the eye may comprise one or more of many axes of theeye, in accordance with embodiments as described herein. In manyembodiments the visual axis comprises an axis extending from thefixation light 119 to the anterior optical nodal point of the eye N, inwhich the anterior optical nodal point of the eye N is located along theoptical axis of the eye 43AO. The visual axis of the eye can extend fromthe posterior nodal point of the eye 43NP to the center of the fovea FV,with an angle α (Alpha), extending between the optical axis and thevisual axis.

Alternatively, the visual axis of the eye may comprise an imaginarystraight line passing from the fixation light located at the midpoint ofthe visual field, through the pupil, to the center of the fovea 43FVwhen the patient fixates on the fixation light, for example. A person ofordinary skill in the art, based on the teachings of the presentdisclosure, will recognize that the imaginary straight line of thevisual axis can be approximated by a line extending between the anteriornodal point of the eye and the posterior nodal point of the eye, forexample approximated with a single “nodal” point of the eye. Forexample, the eye may comprise a single index of refraction to providethe single nodal point of the eye, for example with Gullstrand's reducedschematic eye model. However, in many embodiments as described hereinthe eye comprises two or more indices of refraction, for example threeor more indices of refraction, and the image guided treatment asdescribed herein will provide treatment planning to the user in responseto identification of the visual axis of the eye extending from theanterior nodal point of the eye to the fixation target and from theposterior nodal point of the eye to the fovea.

An angle γ (Gamma) can extend between the optical axis and the fixationaxis, for example. An angle κ (Kappa) can extend between the visual axis43VA and the pupillary axis 43PA, for example. Alternatively, angle κ(Kappa) can be defined so as to extend between the pupillary axis 43PAand the line of sight, for example. In many embodiments, the pupillaryaxis comprises a line extending normal to the surface of the cornea andthrough the center of the pupil, for example.

FIG. 7C shows an anterior view of an eye 43 as in FIGS. 7A and 7B. Theview shows structure of the eye similar to the views of FIGS. 7A and 7B.In many embodiments, the images of FIGS. 7A and 7B are obtained with atomography system such as an OCT system and the image of FIG. 7C isobtained with a video camera such as an alignment camera as describedherein. The dimensions of coordinate system 650 can be aligned for eachof the measurement systems of measurement system 150, and can define themeasurement axis of the eye.

The image of the eye may comprise one or more structures that can beused to identify one or more treatment axes of the eye and structuresand optical tissue surfaces of the eye as described herein, which can becombined with data from one or more of the tomography or the tomographysystem as described herein to determine treatment axis and alignment ofthe eye, for example. The structure of the image of the eye may comprisean image of a marker of the eye such as an ink dot 43ID placed by ahealth care provider such as a physician or an ophthalmic technician,which can be used for alignment of the eye such as cyclo torsionalalignment of the eye around one or more optical axes of the eye asdescribed herein. The ink dot 43ID may comprise a plurality of ink dots,for example a plurality of ink dots on a plurality of opposing sides ofthe pupil. The structure of the image of the eye may comprise images ofblood vessels 43BV that can be used for alignment of the eye, such ascyclo torsional alignment of the eye around one or more axes of the eyeas described herein, for example. The structure image of the eye maycomprise structure of the iris that can be used for alignment of theeye, such as torsional alignment of the eye around one or more axes ofthe eye as described herein, for example.

The eye may comprise a treatment one or more treatment axes, such astreatment axis 43TA, and the location of treatment axis 43TA can dependupon the layer and tissue structure of the eye being treated, forexample the lens or the cornea. The treatment axis 43TA may comprise anaxis of an aberration of the eye such as an astigmatism of the eye or ahigher order aberration of the eye such as coma or trefoil of the eye,for example. The treatment axis 43A can be identified by the system usersuch as a physician, and can be defined to have a center correspondingto one or more of the optical axes as described herein such as one ormore of the vertex of the cornea, the line of sight of the eye, thevisual axis of the eye, or the visual axis of the eye extending from theanterior node of the eye. Alternatively or in combination, the axisidentified by the user can be different for the type of treatment of theeye. For example, with arcuate incisions such as limbal relaxingincisions, the treatment axis may comprise the line of sight or thevertex of the cornea, or other axis as described herein. With anintraocular lens to be placed, the treatment axis may comprise a centerof the real pupil, a center of the line of sight, a center of the visualaxis extending from an anterior node of the eye, or other axis asdescribed herein, for example. Merely by way of example in accordancewith embodiments, the treatment axis 43A is shown with reference to theline of sight 43 LOS corresponding to the center of the entrance pupilwhen the patient fixates on light 119 and the eye is viewed with thevideo camera as described herein, for example.

Each of images 7A to 7C can be shown on the display as described hereinto the user for planning the locations of incisions in relation to oneor more user identified axes of the eye as described herein, forexample.

FIGS. 7D and 7E show an eye as in FIGS. 7A to 7C coupled to a patientinterface for treatment, in which the eye has one or more of rotated ortranslated relative to one or more of three axes of the measurementsystem eye as described herein. The structures of the eye correspondingcoordinate system 650 having dimensions along the axes of the eye forthe initial measurements of the eye, such as dimension 652, dimension654 and dimension 656 have rotated and translated with respect to thecoordinate reference system 150 of the eye 43. The coordinate referencesystem 150 may comprise the coordinate reference system when the eye iscoupled to the patient interface, for example contacts the patientinterface, as described herein. The initial measurement coordinatereference system 650 comprising first dimension 652, second dimension654 and third dimension 656 are show rotated and translated with respectto the eye coordinate reference system 150 when the patient interface iscoupled to the eye with contacts to eye as described herein.

Referring to FIG. 7D, the optical axis of the eye 43AO can be aligned soas to extend away from the axis 99 of the optical delivery system of thepatient interface and laser system. The alignment of the axes of the eyeto the axis 99 of the optical delivery system can be determined in oneor more of many ways.

The physician can perform one or more of many steps to align the eye 43with axis 99 of the optical delivery system of the patient interface ofthe laser system as described herein. In many embodiments, the axis 99of the optical delivery system is shown on the display, for example witha reticle, and the reticle on the display used to align the eye with theaxis 99 of the optical delivery system. The reticle shown on the displaymay correspond to dimension 152, 154 and 156 of eye coordinate referenceframe 150 when the eye contacts the patient interface. For example, thepatient can be asked to view the fixation light 119 and the laser systemaligned with one or more structures of the eye as described herein, suchas the limbus of the eye, for example. Alternatively or in combination,the axis 99 can be aligned with the vertex of the cornea, for example.In many embodiments, the physician can align the axis 99 with the centerof the light reflected from the front surface of the cornea, forexample. Alternatively or in combination, the axis 99 of the system canbe shown on the display when the patient views the fixation light, and alocation of the vertex 43VX from prior to contact can be shown on thedisplay and the

Referring again to FIGS. 7D and 7E, the structures of the eye 43A areshown rotated and translated for the measurements prior to the eyecontacting the patient interface and the measurements with the eyecontacting the patient interface. The ink dot 43ID is shown rotated andtranslated with respect to the location prior to the interfacecontacting the eye. The blood vessels 43BV are shown rotated andtranslated with the respect to the locations prior to contacting the eyewith the patient interface. The treatment axis 43TA is shown rotated andtranslated with respect to the locations determined prior to the patientinterface contacting the eye.

One or more of the tissue structures of the eye can change when the eyehas contacted the patient interface. With surgery, the eye may comprisea dilated pupil PUD that can dilate eccentrically with respect to thenatural pupil PUN. The location of the capsulorhexis incision 43CX canbe determined based on the natural pupil of the eye, for example. Inmany embodiments, the capsulorhexis incision is centered on the naturalline of sight 43LOSN determined from the initial images prior tocontacting the eye with the patient interface, for example.Alternatively or in combination, the capsulorhexis incision may becentered on the visual axis of the eye 43VA extending from the anteriornodal point of the eye as described herein. The location of the vertex43VX of the cornea determined without contact to the eye can be shown onthe display as the location of the vertex of the cornea can change, forexample when the patient interface distorts the cornea.

The locations of the limbal relaxing incisions 43LRI can be determinedin one or more of many ways and can be centered on the natural line ofsight 43LOSN corresponding to the line of sight 43LOS determined priorto contacting the eye, for example. Alternatively or in combination, thelocations of the limbal relaxing incisions can be centered on the vertex43VX of the cornea determined prior to the patient interface contactingthe cornea, and the location of corneal vertex 43VX prior to the patientinterface contacting the cornea can be displayed to the user to for useas a reference point to center the limbal relaxing incisions 43LRI, forexample.

In response to movement of the eye relative to the initial measurementaxis and the axis 99 of the laser system, the treatment axis 43TA of theeye can be seen as rotated in relation to the coordinate reference frame150 of the eye coupled to the laser system.

FIG. 7F shows rotation and translation of the measurement coordinatereference system 650 relative to the eye coordinate reference system 150when the eye has contacted the patient interface, in which the rotationand translation of the measurement system 650 prior to contact with thepatient interface corresponds to rotation and translation of the eyerelative to the coordinate system 150 when the patient interfacecontacts the eye. The rotation and translation of one or more of thetissue structures of the eye determined with the natural pupil andvision of the eye can be correspondingly rotated and translated andprovided on a display for the physician to determine the treatment ofthe eye. The locations and orientations of the tissue structures of theeye determined with measurements of the eye prior to coupling with thepatient interface can be mapped from the coordinate system 650 to thecoordinate 150 and shown on the display with the image of the eyecoupled to patient interface. This allows the user to determine thetreatment with the coordinate reference 150 with the eye contacting thepatient interface, while showing the locations of the structures of theeye from used for natural vision from the coordinate reference frame 650on the patient interface.

FIG. 7G shows an optical schematic of the eye as in FIGS. 7A and 7B,with structures of eye including the cardinal points of the eye and axesof the eye useful for vision. In many embodiments, one or morestructures of the optical schematic of the eye are projected onto thedisplay and aligned with the image of the eye shown on the display inorder for the user to plan the incisions and surgical treatment of theeye.

In many embodiments, one or more of the tissue structures of each ofimages 7A to 7G can be shown on the display to the user for planning thelocations of incisions as described herein, such as the location of thenodal points of the eye along the optical axis of the eye, the line ofsight of the eye, the vertex of the cornea, and the visual axisextending from the anterior nodal point of the eye. For example, the oneor more structures of the optical schematic of the eye determined frommeasurements prior to contacting the eye can be shown on the displayaligned with images of the eye obtained when the patient interface hascontacted the eye, in order for the surgeon to determine the locationsof incisions in alignment with the one or more structures of the eyedetermined from measurements obtained prior to contact with the patientinterface when the patient interface contacts the eye. Alternatively orin combination, the one or more optical structures of the eye shown onthe display can be determined in response to measurements obtained whenthe patient interface contacts the eye, for example for comparison withlocations of the one or optical structures determined from measurementsobtained prior to the patient interface contacting the eye.

FIGS. 8A, 8B and 8C show images of a user interface display configuredto show one or more optical structures of the eye to position the laserbeam pulses of a tissue treatment in order to treat the eye. The imagesof the eye shown on the display may comprise one or more of an axialimage of the eye, a sagittal image of the eye, or an anterior view ofthe eye, for example. Each of the images may comprise one or moremarkers to show one or more tissue structures of the eye, in accordancewith embodiments. For example, one or more axes of the eye can be shownwith one or more markers placed on the display at locations of the imageof the eye to identify the location of the corresponding one or moreaxes of the eye. In many embodiments, one or more of the tissuestructures of FIGS. 8A, 8B and 8C can shown on the display withcorresponding marks placed over the image of the eye to show thelocation of the one or more tissue structures of the eye in relation tothe eye prior to coupling the eye to the patient interface.

FIG. 8A shows an image 680 of the eye obtained with a tomographyapparatus as described herein when the eye contacts the patientinterface. The image 680 may comprise an image of a mydriatic eye 43M.The mydriatic eye 43M may comprise an eye treated with a mydriaticsubstance such as a cycloplegic agent in order to dilate the eye tovisualize the lens 43L and allow access to the lens capsule with thelaser beam and tomography beam. The image 680 may show a dilated pupil43PUD having a dilated pupil center 43PUDC. The cornea coupled to thepatient interface can be distorted slightly such that the vertex of thecornea has shifted to a distorted vertex 43VXD. The image 680 may show alens of the eye treated with the mydriatic substance, such that the lenscomprises a mydriatic anterior lens capsule 43LACM and a mydriaticposterior lens capsule 43LPCM, in which the mydriatic anterior lenscapsule and mydriatic posterior lens capsule may be shifted posteriorlyrelative locations of the anterior lens capsule 43LAC and posterior lenscapsule 43LPC measured prior to the patient interface contacting theeye, for example.

The eye 43 coupled to the patient interface can be displayed with amarker showing axis 99 of the optical delivery system aligned with thecoordinate reference frame 150 of the eye, although axis 99 andcoordinate reference frame 150 can be aligned in one or more of manyways and separate markers can be used to indicate the location of theaxis and the center of the reference frame in accordance with theembodiments described herein. The markers of the eye can be shown withone or more axes of the eye rotated away from the axis 99 of the patientinterface. Alternatively or in combination, one or more axes of the eyecan be aligned with the axis 99 of the patient interface when thepatient interface contacts the eye. Although the eye 43 is shown with adilated pupil and a corresponding non-accommodative lens, the eye can becoupled to the patient interface without dilation of the pupil, forexample.

The structures of the eye measured prior to the patient interfacecontacting the eye can be shown with markers on the display along withimage 680 of the eye obtained when the patient interface has contactedthe eye, in order to determine locations of laser incisions when the eyehas contacted the patient interface. The locations of referencestructures of the eye as described herein can be measured and one ormore of the rotation or translation of the eye between the non-contactmeasurements and the contact measurements determined, for example.

The locations of one or more structures of the eye prior to contactingthe interface can be shown on the display 12 with markers placed on theimage 680, in order for the user to position the laser incisions on theeye contacting the patient interface with reference to locations the oneor more structures prior to the eye contacting the patient interface.The pre-contact interface contact optical structure shown on the displaywith markers placed on image 680 may comprise one or more of, theoptical axis 43AO, the pupillary axis 43PA, the line of sight 43LOS, thevisual axis 43VA, the fixation axis 43FA, the natural pupil 43PUN, theanterior principal point 43AP, the posterior principal point 43PP, theentrance pupil 43ENP, the natural pupil center 43PUC, the exit pupil43EXP, the anterior nodal point 43NA, or the posterior nodal point 43NP,for example. Alternatively or in combination, the optical structureshown on the display may comprise one or more optical structures of theeye when the interface has contacted the eye, such as one or more of theoptical axis of the eye of image 680, the dilated pupillary axis, theline of sight of the dilated pupil, the visual axis of the mydriatic eyewhen the patient views the fixation light 119, the fixation axis, thedilated pupil 43PUD, the anterior principal point of the dilated eye ofimage 680, the posterior principal point of the dilated eye of the image680, the entrance pupil of the dilated eye, the pupil center 43PUCD ofthe dilated pupil, the exit pupil of the mydriatic eye, the anteriornodal point of the mydriatic eye, or the posterior nodal point of themydriatic eye, for example.

The image 680 of the eye can be shown to the user, and the user candetermine one or more axis of the eye to display on the image of theeye, for example in response to user preference. The display andprocessor can be configured to receive user input, and the user mayidentify one or more axis of the eye as described herein to use asreference locations to place the capsulotomy, such as a capsulorhexis,and volume of material to be incised with the laser, for example.Alternatively or in combination, the user may identify one or more axesof the eye for corneal surgery of the eye as described herein. Forexample, the user may identify one axis to use as a reference to centerthe capsulorhexis incision, and another axis to center the cornealrefractive procedure, although the same axis can be used for both.

The locations of the incisions of the eye can be determined at least inpart in response to locations of the optical structures of the eye priorto the eye contacting the patient interface, for example. The locationof the capsulorhexis 43CX can be determined in relation to the markershowing the natural pupil of the eye 43PUN, for example. Thecapsulorhexis 43CX can be centered one or more of the line of sight43LOS, the natural entrance pupil 43ENP, the physical center of thenatural pupil 43PC, the center of the exit pupil 43EXP, the naturaloptical axis 43AO, or the visual axis 43VA, for example. As shown inFIG. 8A, the planned capsulorhexis is shown with a marker centered inrelation to the natural pupil of the eye 43PUN.

Work in relation to embodiments suggests that positioning theintraocular lens in relation to the anterior node of the eye, forexample along the visual axis extending from the anterior node of theeye, can decrease deflection of the rays entering the eye when the IOLhas been placed. For example, the IOL may comprise a nodal pointcorresponding substantially to the center of the IOL, and centering theIOL in relation to the anterior nodal point of the eye such that the IOLis aligned with the visual axis extending from the anterior nodal pointcan maintain the natural visual axis of the eye and inhibit deflectionof the natural visual axis when the lens has been placed. In manyembodiments, the capsulorhexis can be centered on the visual axis 43VAextending from the anterior node 43NA spaced apart from the posteriornode 43NP, for example. The display and processor can be configured toshow the visual axis 43A extending from the node on the display alignedwith image 680 of the eye. Alternatively or in combination, structurescan be incised in the lens capsule to inhibit movement of the lens inrelation to the visual axis of the eye, for example. The structuresincised in the lens may comprise incisions sized to receive protrudingstructures of the IOL to hold the IOL in place, for example. In manyembodiments, markers indicating the locations of the structures toreceive the protrusions are shown on the display.

One or more structures of the eye of image 680 can be used to identifythe locations of incisions of the eye. For example, the laser can beconfigured to remove tissue from an incision volume 43VR of the eyedefined and incision volume profile 43VRP. The incision volume 43VR andcorresponding profile 43VR can be shown on the display to the user withthe optical structures of the eye as described herein. The incisionvolume 43VR can define a volume of tissue to be incised with laser basedvolumetric photo fragmentation, for example. The incision volume profile43VRP can be shown on the display positioned on image 680, for example.

The limbal relaxing incisions 43I are shown aligned with natural vertexof the cornea 43VX located along the optical axis 43AO, although one ormore of many locations as described herein as described herein can beused as a reference to position the cornea incisions, for example. Thelimbal relaxing incisions 43LRI may comprise arcuate incisions having acenter located along the optical axis of the eye 43AO, for example.

Although the eye is show coupled to an interface with the cornea awayfrom solid structures of the interface, the embodiments as describedherein can be combined with patient interfaces that flatten the corneaof the eye contact of the cornea to the interface, for example with anapplanating the patient interface.

FIG. 8B shows an image 682 of anterior view of the eye as can be seenwith the alignment camera and one or more tissue structures of the eyeshown on the display for alignment of the eye, such as one or moreoptical tissue structures shown on the display for alignment of acorneal surgical procedure. The image 682 may show a dilated eye 43D asdescribed herein, for example. The image 680 of the eye can be shownwith reference axes of the coordinate reference systems as describedherein. The axis 99 of the optical delivery system can be shownsubstantially aligned with the eye coordinate reference system 150 ofthe eye contacting the patient interface as described herein. The imageof the eye may show the dilated pupil of the eye 43PUD. The referenceaxes can be shown at locations on the cornea of the eye in order toalign the eye with one or more corneal surgical procedures as describedherein, for example. The optical structures of the natural eye are shownat locations of the cornea and may comprise one or more opticalstructures determined in response to measurements obtained prior tocontacting the eye with the patient interface such as one or more of thevertex of the cornea 43VX, the line of sight 43LOS, and the visual axis43VA, for example. The locations shown on the display can be one or moreof rotated or translated in response to measurements of the eye obtainedwhen the eye contacts the patient interface. For example, the referenceaxis obtained prior to the patient contacting the interface may comprisedimension 654 one or more of rotated or translated in response tomeasurements of the eye as described herein. The treatment axis 43TRAcan be one or more of rotated or translated as shown on the display forthe user to plan the incisions of the eye, for example. The measurementaxis can be one or more of rotated or translated about one or more axisas described herein, for example shown on the display rotated about thenatural vertex of the cornea 43VX extending along the optical axis 43AO,for example. The ink dot 43ID that may have been placed on the eye canbe shown on the image of the eye shown on the display, for example.

In many embodiments image 682 comprises a real time image from thealignment video camera shown on the display 12, and the axes of the eyeand reference points are projected on the real time display, forexample.

FIG. 8C shows an image 684 of anterior view of the eye as can be seenwith the alignment camera and one or more tissue structures of the eyeshown on the display for alignment of the eye, such as one or moreoptical tissue structures shown on the display for alignment of acorneal surgical procedure. The image 684 may comprise one or morestructures of image 682, for example. The image 684 shows the dilatedpupil 43PUD and the coordinate reference system 150 aligned with theeye. The dilated pupil center 43PUDC can be offset from the naturalpupil 43PUN. The capsulorhexis incision 43CX can be aligned with one ormore of the natural pupil 43PUN, the line of sight 43LOS, the visualaxis 43VA, the axis 99 of the patient interface, the limbus 43LI, thedimension 156 of the coordinate reference system 150, or the dilatedpupil center 43PUDC, for example. In many embodiments, the capsulorhexisincision is aligned with the natural pupil center 43PC of the eye.

The images of FIGS. 8A, 8B and 8C merely provide examples in accordancewith some embodiments, and these figures can be combined in one or moreof many ways in accordance with additional embodiments. For example, theimages of FIGS. 8A and 8B can be combined to form a single image on thedisplay, and the markers used to identify the tissue structures can beoverlaid on a live image from the alignment video camera as describedherein, for example. In many embodiments, the markers of the referencelocations of the eye are shown on the display when the laser beamincises the tissue in order for the user to verify the placement of thelaser beam incisions at the targeted locations.

FIG. 9 shows a tomographic image of an eye 43 with an eccentric pupil43PU and determination of the optical axis 43AO of the eye. The image ofthe eye may comprise an image of the eye obtained without the patientinterface contacting the eye or an image of the eye measured with thepatient interface contacting the eye. The locations and profiles ofstructures of the eye as described herein can be determined from thetomographic data of the eye. One or more axis of the eye can bedetermined in relation to the optical axis 43AO of the eye as describedherein. In many embodiments, the visual axis extends substantiallyparallel to the measurement axis of the tomography system, and locationof the visual axis determined from the anterior nodal point of the eyeas described herein. The optical axis 43AO extends through the centersof curvature of the lenses of the eye. In many embodiments, the center43PUC of the pupil 43PU of the eye is located away from the optical axis43AO extending through the pupil. The location of the optical axis ofthe eye remains substantially fixed when the pupil of the eye dilates.

In the embodiments shown, the optical axis of the eye can be determinedso as to provide accurate determination of the structures of the eye inorder to accommodate variability among eyes and changes of tissues of aneye of a subject. The optical axis of an eye of a subject can beaccurately determined when the pupil constricts and dilates and theaccommodation of the lens changes, for example. For example, theembodiments shown in FIG. 9 illustrate the fovea located about 2.5×further from the optical axis than a normal eye, and the pupil is showndisplaced in a temporal direction. For example, the center of the pupilcan be displaced nasally or temporally away from the optical axis andthe location of the optical axis remains substantially fixed when theoptical axis has been determined in response to locations of the centersof curvature. In many embodiments, the pupillary axis extends throughthe center of the entrance pupil and the center of curvature of thecornea, and the pupillary axis can be located on the nasal side of theoptical axis or the temporal side of the optical axis, for example.

The location of the optical axis can be determined in response to thelocations of the centers of curvature of one or more of the anteriorcorneal surface 43CAS, the posterior corneal surface 43CPS, the anteriorlens capsule surface 43LAC, the posterior lens capsule surface 43LPC,and combinations thereof, for example. The anterior corneal surface43CAS has a center of curvature 43C1, and the posterior corneal surface43CPS has a center of curvature 43C2. The anterior lens capsule 43LAChas a center of curvature 43C3, and the anterior corneal surface 43CAShas a center of curvature 43C1. Each of the centers of curvature can bedetermined in three dimensional space with respect to the eye coordinatereference system 150, and the locations of the centers of curvature usedto determine the optical axes of the eye. The optical axis of the eyecan be oriented and positioned so as to decrease the separation distanceof the optical axis of the eye to the centers of curvature. For example,the optical axis can be determined with least squares fitting so as tominimize the distances from the optical axis to the centers ofcurvature. In many embodiments, the optical axis extends through thecenters of curvature of the eye.

The centers of curvature of the optical surfaces of the eye can bedetermined in one or more of many ways. For example, tomography data ofeach surface can be fit to determine the center of curvature, and thelocations of each of the centers of curvature determined. In manyembodiments, one or more of the surfaces may deviate from a sphere, andthe center of curvature determined from least squares approximate of thecenter of surface. Alternatively or in combination, the surface can befit to an elliptical or other surface, and the centers of curvaturedetermined from the fit surface. For example, the fit surface maycomprise a three-dimensional elliptical surface, and the locations ofthe foci of the ellipse used to determine the center of the ellipse. Theoptical surface of the eye may comprise a toric surface, and the centersof curvature of portions of a surface fit to the tonic optical surfaceused to determine locations of the center of curvature of the eye. Inmany embodiments, the optical surface of the eye is fit with one or morewith one or more of a Fourier transform, polynomials, a sphericalharmonics, Taylor polynomials, a wavelet transform, or Zernikepolynomials.

In many embodiments, the processor comprises instructions to fit profiledata of the optical surface of the eye with one or more with one or moreof a Fourier transform, polynomials, a spherical harmonics, Taylorpolynomials, a wavelet transform, or Zernike polynomials. Each fitoptical surface of the eye can be used to determine the center ofcurvature of the optical surface, and the centers of curvature used todetermine the optical axis of the eye. The optical axis of the eye canthen be used to reference one or more structures of the eye, such asaxis of the eye, when the eye contacts the patient interface. In manyembodiments, the non-contact optical axis of the eye is determined whenthe eye is free to fixate without contacting the patient interface, andthe contact optical axis is determine when the eye contacts the patientinterface.

Several structure optical structures of the eye can be identified inrelation to the non-contact optical axis measured when the eye is freeto move and view and object, and these optical structures mapped ontothe eye contacting the patient interface, in response to locations andorientations of the contact optical axis and the non-contact opticalaxis. The orientation may comprise an orientation of the optical axisand a cyclotorsional angle of rotation about the optical axis or otheraxis extending in an anterior-posterior direction such as the fixationaxis, the line of sight, or the pupillary axis, for example.

FIG. 10 shows a first optical axis 43AO1 of a non-contact measurementand a second optical axis 43AO2 of a contact measurement, in which thefirst and second optical axes can be used to determine locations ofstructures of the eye when the eye contacts the patient interface. Thefirst optical axis 43AO1 extends through a first center of curvature43C11, a second center of curvature 43C21, a third center of curvature43C31, and a fourth center of curvature 43C41, for example. The secondoptical axis 43AO2 extends through a first center of curvature 43C12, asecond center of curvature 43C22, a third center of curvature 43C32, anda fourth center of curvature 43C42, for example.

The first optical axis 43AO1 extends through a first anterior nodalpoint 43NA1 of the eye and a first posterior nodal point 43NP1 of theeye. A first visual axis 43VA1 extends from the first anterior nodalpoint 43NA1 to a fixation light such as fixation light 119 as describedherein. The path of the visual axis can be determined from the locationof the anterior nodal point of the eye and the location of the fixationlight, which can be placed such that the visual axis 43A1 extendssubstantially parallel to measurement axis 699 the longitudinaldimension 656 of non-contact coordinate reference system 650, forexample. The first optical axis can be used to define a first cyclotorsional angle 43CTA1 of the eye and a first treatment axis of the eye43TA1. The first optical axis extends to a first location of the retina43R1 that may be located on a first location of the fovea 43FV1. Thefirst distances from the retina to the centers of curvature can be usedto define the locations of structures of the eye, and to identifydistortion of the eye. The non-contact coordinate reference system 650may comprise the coordinate reference system of a separate diagnosticimaging device as described herein, or the coordinate reference system150 of the laser system 2 prior to contacting the eye with the patientinterface, for example. In many embodiments, the first locations of thefirst centers of curvature are determined with reference to coordinatereference system 650.

One or more of the optical structures of the eye can be difficult todetermine when the patient interface contacts the eye, as the eye maynot move freely, and the fixation light, if present can be blurry in atleast some embodiments. For example the line of sight, visual axis, andtreatment axis can be difficult to identify when the eye contacts thepatient interface. The locations of one or more of the line of sight,visual axis, or the treatment axis can be determined in accordance withthe embodiments disclosed herein.

The axes of the eye can be determined in one or more of many ways whenthe patient interface contacts the eye in accordance with embodimentsdisclosed herein. For example, the second optical axis 43AO2 extendsthrough a second anterior nodal point 43NA2 of the eye and a secondposterior nodal point 43NP2 of the eye when the eye contacts the patientinterface. A second visual axis 43VA2 extends from the second anteriornodal point 43NA2. The path of the second visual axis 43VA2 can bedetermined from the location of the second anterior nodal point 43NA2and the orientation and angles of the first visual axis 43VA1 withrespect to the first anterior nodal point 43NA1, such that the secondvisual axis 43VA2 extends from the second anterior nodal point 43NA2 andthe second optical axis 43AO2 with angles similar to the first visualaxis 43VA1 extending from the first anterior nodal point 43NA1 and firstoptical axis 43AO1. The second optical axis can be used to define asecond cyclo torsional angle 43CTA2 of the eye and a second treatmentaxis of the eye 43TA2. The second treatment axis 34CTA2 can bedetermined in response to cyclotorsion of the eye about the optical axis43AO when the eye 43 rotates from first cyclotorsional angle 43CTA1 tosecond cyclotorsional angle 43CTA2. In many embodiments, difference inangle between the second cyclotorsional angle 43CTA2 and firstcyclotorsional angle 43CTA1 is determined, the second treatment axis43TA2 is determined in response to the difference in the cyclotorsionalangle of the eye. Although reference is made to the cyclotorsionalangles, in many embodiments, correction for changes in head tilt withrespect to the measurement axis can be provided with measurement of thetorsional angles of the eye around the optical axis as described herein.For example, the head of the patient can tilt from the first measurementto the second measurement, and the measurement of the cyclotorsionalangle of the eye can correct for the head tilt.

The second optical axis extends to a second location of the retina 43R2that may be located on a second location of the fovea 43FV2. The seconddistances from the retina to the centers of curvature can be used todefine the locations of structures of the eye, and to identifydistortion of the eye, for example when these distances vary between thefirst non-contact measurements and the second contact measurements. Thecontact coordinate reference system 150 may comprise the coordinatereference system 150 of the laser system 2 when the patient interfacecontacts the eye, for example.

In many embodiments, the first locations of the first centers ofcurvature are determined with reference to coordinate reference system650 for non-contact measurements, and the locations of the secondcenters of curvature are determined with coordinate reference system 150when the eye contacts the patient interface. For example, the coordinatereference system 150 of the laser system can be used for firstnon-contact measurements of the eye and comprises the non-contactcoordinate reference system 650, and the second contact measurements ofthe eye may comprise the coordinate reference system 150, in which thelocations of the structures of the eye can be mapped from the firstlocations of coordinate reference system 650 to the second locations ofcoordinate reference system 150, in order to determine locations ofoptical structures of the eye when the patient interface contacts theeye, such as the visual axis and line of sight as described herein.

In many embodiments, each center of curvature may comprise a narrowcross-section of a bundle of light rays normal to the optical surface ofthe eye that do not coincide at a single point, and the center ofcurvature may comprise a volumetric region of space defined with thebundle of rays similar to a circle of least confusion. Although thefirst centers of curvature may not lie exactly on a line, the firstoptical axis as described herein can be considered to extend through thefirst centers of curvatures when the first optical axis is located andoriented to decrease separation of the first optical axis to each of thefirst centers of curvature. Although the second centers of curvature maynot lie exactly on a line, the second optical axis as described hereincan be considered to extend through the second centers of curvatureswhen the first optical axis is located and oriented to decreaseseparation of the second optical axis to each of the second centers ofcurvature.

In many embodiments, the location and orientations of the first opticalaxis 43VA1, the second optical axis 43VA2, the first cyclotorsionalangle 43CTA1, and the second cyclotorsional angle 43CTA2, can be used todetermine parameters of a coordinate mapping function in order todetermine locations of first tissue structures of the eye on an image ofthe eye contacting the patient interface shown on the display asdescribed herein. For example, the locations of one or more of the firstvisual axis, the first pupil, or the first line of sight can be shown onthe image of the eye contacting the patient interface, which maycomprise a real time image of the eye, for example.

The structures of the eye can be mapped from the first non-contactcoordinate reference system 650 to the second coordinate referencesystem 150 in one or more of many ways. For example, the location andorientation of the second optical axis can be determined and used as areference axis to map structures of the eye such as one or more of thenatural pupil of the eye, the visual axis of the eye, the line of sightof the eye, or the treatment axis of the eye, and combinations thereof,for example. In many embodiments, the cyclotorsional angle of the eyearound the optical axis is determined in each of the first non-contactcoordinate reference system 650 and the second coordinate referencesystem 150, and the structures of the eye mapped from the firstnon-contact coordinate reference system to the second coordinatereference system in response to the angles, for example in response to achange in the first cyclo torsional angle and the second cyclo torsionalangle.

In many embodiments, the coordinate reference locations of thestructures of the eye from the first non-contact measurements ofcoordinate reference system 650 are mapped to coordinate referencelocations of the second measurement coordinate reference system 150. Inmany embodiments a mapping function is determined in order to map thestructures of the eye from the first non-contact measurements to thesecond contact measurements for display on images obtained when theinterface contacts the eye as described herein. In many embodiments, themapping function takes the form of:

(X2, Y2, Z2)=M(X1, Y1, Z1)

Where X1, Y1, Z1, are the X, Y and Z coordinates along dimensions 652,654 and 656, respectively, of first non-contact reference coordinatesystem 650, and X2, Y2, Z2, are the X, Y and Z coordinates alongdimensions 152, 154 and 156, respectively, of the second referencecoordinate system 150, for example. A person of ordinary skill in theart can determine the mapping function M(X1, Y1, Z1) with the firstlocations first structures of the eye and second locations of secondstructures of the eye, in accordance with the teachings disclosedherein. In many embodiments, the mapping function is determined withlocations of the first centers of curvature and the first cyclotorsionalangle and the second centers of curvature and the second cyclotorsionalangle, for example.

In embodiments where the first measurement comprises a non-contactmeasurement of an eye at a separate diagnostic device and the secondmeasurement comprises a non-contact measurement from the laser system,the coordinate references can be similarly transformed to determinelocations of the structures of the eye as described herein. In manyembodiments, the second non-contact measurement of the eye can be usedto align the treatment axis 43TRA of the eye with the laser system, forexample in order to determine the second treatment axis 43TRA2 inresponse to an astigmatic axis of the eye as described herein.

While the topography measurement system can be coupled to the lasersystem in many ways, in many embodiments the topography measurementsystem comprises a coupling structure to couple a topography measurementstructure to the patient interface.

FIGS. 11A-11E show a topography measurement structure configured tocouple to a patient interface 52 as described herein to measure the eyeprior to the eye contacting the patient interface. The topographymeasurement structure may comprise one or more of a ring or otherstructure for a keratometry reading of the eye, a Placido disctopography of the eye, a reflection of a plurality of points from thecornea topography of the eye, a grid reflected from the cornea of theeye topography. In many embodiments, the measurement structure comprisesa Placido disc structure configured to couple to a component of thepatient interface, for example. The topography measurement structure canbe illuminated, for example, so as to form a virtual image of themeasurement structure when reflected from the cornea. One illuminationstrategy could make use of the internal existing illuminator of thesystem itself. Alternatively or in combination, the topography structuremay comprise a ring illuminator either mounted to the patient interfaceor to the structure of the laser system.

In many embodiments, topography measurement structure is backilluminated with light from the laser system to illuminate the eye withthe topography measurement structure. Alternatively or in combinationthe topography measurement structure may comprise a plurality of lightsources such as light emitting diodes to illuminate the eye with thetopography measurement structure.

FIG. 11B shows the topography measurement structure removable coupled tothe patient interface to position the topography measurement structurein relation to the eye when the patient has been placed on the supportof the laser eye surgery system as described herein. The OCT measurementbeam can be used to position the eye. This use of the OCT measurementbeam may be particularly important to achieve absolute curvaturereadings of the Placido system as the diameter of the reflected Placidorings may depend not only on the curvature of the cornea but also fromthe distance of the ring illuminator and the cornea. OCT can help tominimize these variations. Additionally, this measurement informationcan also be used to actively track position the patient's chair and movethe eye into the correct or desired position. Additionally, the OCTsystem and optionally also the camera can be used to locate the actualposition of the Placido ring in relation to the system to enable highprecision measurements. Alternatively or in combination, the focus ofthe video camera as describe herein can be used to position the eye formeasurement. When the topography of the patient has been measured andthe axis determined, for example, the topography measurement system canbe decoupled from the patient interface structure and the patientinterface coupled to the eye as described herein.

The Placido disk illuminator can be constructed in many different ways.Having a clear aperture in the center of the ring structure to allow thevideo system to be used as is may be particularly important. Otherembodiments may comprise a combination of different engineered diffusersand masks which can be optimized on the diffusing angle used to thedetection of the rings from the cornea. Or, if polarized light is used,a combination of quarter wave plate or depolarizer and diffuser withring apertures can be used. For full utilization, the light illuminatedon the blocked rings can make the blocked rings act as reflecting wedgesso the light is fully utilized. In such cases, an angle which enablestotal reflection may be helpful. Utilizing a combination of a strongnegative lens and the Placido disk illuminator can also increase thelight intensity of the outer rings for better contrast.

In many embodiments, the topography measurement structure comprises anexternal illumination structure such as a ring illuminator illuminatesthe eye to form a ring shaped virtual image of the illuminationstructure, and the astigmatic axis of the eye determined based onmeasurements of the virtual image of the eye as described herein. Theexternal illuminator can be configured to couple to the patientinterface for measurement of the eye and removed when the eye has beendocked to the patient interface. Alternatively, the external illuminatormay comprise a substantially fixed structure that remains fixed to thelaser system throughout a plurality of procedures.

The corneal topography data and thickness data can be combined in one ormore of many ways. For example, the corneal topography data can be usedto determine the shape profile of the anterior corneal surface, and thecorneal thickness profile data can be fit to the anterior cornealsurface profile in order to determine the profile of the posteriorsurface, for example. In many embodiments, the anterior corneal surfaceprofile is measured and determined without the patient interfacecontacting the eye, and the corneal thickness profile is measured anddetermined when the patient interface contacts the eye. The cornealsurface profile data measured without contacting the eye can be combinedwith the corneal thickness profile data measured with the patientinterface contacting the eye, and the location of refractive incisionsdetermined in response to both profiles, for example.

FIG. 11B shows components of the patient interface and the topographymeasurement structure configured to couple to the patient interface.

FIG. 12 shows a method 700 of treating an eye with a laser beam.

Method 700, the steps of the method 700 comprise one or more of thefollowing steps.

At a step 705, the eye is identified.

At a step 710, the patient is placed on the support for measurement.

At a step 715, provide fixation light for eye.

At a step 720, patient views fixation light.

At a step 725, align eye with measurement apparatus.

At a step 730, define non-contact measurement reference axes.

At a step 735, measure topography of eye without patient interfacecontacting eye.

At a step 740, measure tomography of eye without patient interfacecontacting eye.

At a step 745, capture Iris image of eye without patient interfacecontacting eye.

At a step 750, determine keratometry axes of eye.

At a step 755, determine thickness profile of eye.

At a step 760, determine treatment axes of eye.

At a step 765, identify natural pupil and pupil center of eye.

At a step 770, identify one or more tissue structures of eye measuredwithout patient interface contacting eye comprising one or more oflimbus, sclera, blood vessels, iris, pupil, pupil center, natural pupil,natural pupil center, cornea, cornea anterior surface, astigmatic axesof cornea anterior surface, cornea posterior surface, thickness profileof cornea, vertex of cornea, lens, lens anterior surface, astigmaticaxes of lens anterior surface, lens posterior surface, astigmatic axisof lens posterior surface, retina, anterior optical node of eye,posterior optical node of eye, optical axis of eye, line of sight ofeye, pupillary axis of eye, visual axis of eye, nodal axis of eye,center of curvature of anterior corneal surface, center of curvature ofposterior corneal surface, center of curvature of lens anterior surface,or lens posterior surface.At a step 775, determine eye coordinates of the one or more tissuestructures of eye in relation to non-contact measurement reference axes.At a step 780, place patient on surgical support for measurement.At a step 785, provide surgical fixation light for eye.At a step 790, adjust fixation light to focus of the eye.At a step 795, patient views fixation light.At a step 800, align eye with surgical apparatus using indicia of laserdelivery system axis.At a step 805, contact eye with patient interface when patient viewsfixation light and eye is aligned with laser system delivery axis.At a step 810, ask patient if fixation light is centered in visual fieldor to the side.At a step 815, adjust eye in relation to fixation ring if fixation lightto the side of visual field.At a step 820, measure topography of eye with interface contacting eye.At a step 825, measure tomography of eye with interface contacting eye.At a step 830, capture Iris image of eye with interface contacting eye.At a step 835, determine keratometry axes of eye with interfacecontacting eye.At a step 840, determine thickness profile of eye with interfacecontacting eye.At a step 845, determine treatment axes of eye with interface contactingeye.At a step 850, identify dilated pupil and dilated pupil center of eyewith interface contacting eye.At a step 855, identify the one or more tissue structures of eyemeasured with patient interface contacting eye comprising one or more oflimbus, sclera, blood vessels, iris, pupil, pupil center, natural pupil,natural pupil center, cornea, cornea anterior surface, astigmatic axesof cornea anterior surface, cornea posterior surface, thickness profileof cornea, vertex of cornea, lens, lens anterior surface, astigmaticaxes of lens anterior surface, lens posterior surface, astigmatic axisof lens posterior surface, retina, anterior optical node of eye,posterior optical node of eye, optical axis of eye, line of sight ofeye, pupillary axis of eye, visual axis of eye, nodal axis of eye,center of curvature of anterior corneal surface, center of curvature ofposterior corneal surface, center of curvature of lens anterior surface,or lens posterior surface.At a step 860, determine alignment of non-contact eye measurementreference axes in relation to contact eye measurement reference axes inresponse to locations of the one or more tissue structures.At a step 865, determine one or more of an orientation or a translationof the contact measurement axes of the eye in relation to non-contactmeasurement axes of the eye.At a step 870, determine contact eye coordinate references of the one ormore tissue structures of eye without patient interface contacting eyein response to the one or more of rotation, translation, or cyclotorsionwhen the patient interface contacts the eye.At a step 875, determine one or more non-contact treatment axes inresponse one or more of an orientation of a translation of the contactmeasurement axes in relation to the non-contact measurement axes.At a step 880, display the one or more non-contact treatment axes to theuser.At a step 885, display locations of the one or more tissue structures ofthe eye measured without contact to the user, with the locations rotatedand translated in response to the rotation and translation of the eyebetween the non-contact measurement and the contact measurement.At a step 890, determine incision profiles in response to locations oftissue structures measured without eye contact when the patientinterface contacts the eye.At a step 895, determine incision profiles of capsulotomy in response tolocations of tissue structures measured without eye contact when thepatient interface contacts the eye.At a step 900, align capsulotomy with visual axis of the eye shown ondisplay.At a step 905, determine incision profiles of limbal relaxing incisionsin response to locations of tissue structures without eye contact whenthe patient interface contacts the eye.At a step 910, align limbal relaxing incisions on the visual axis of theeye shown on display.At a step 915, incise tissue with laser beam.At a step 920, remove lens of the eye.At a step 925, display reference treatment axes.At a step 930, place intraocular lens in eye.At a step 935, align astigmatic axes of IOL with astigmatic referencetreatment axes of eye on display with rotation of the IOL around thevisual axis.At a step 940, align optical node of IOL with anterior optical node ofeye shown on display.At a step 945, remove patient interface.At a step 950, follow up visit with patient.

FIG. 12 shows a method 700 in accordance with embodiments. Severalmodifications and variations can be provide, such as the steps can beperformed in any order, one or more of the steps may comprise substeps,one or more steps can be removed, one or more steps can be repeated, anda person of ordinary skill in the will recognize many variations inaccordance with method disclosed herein. Further, the circuitry ofsystem 2 as described herein, for example the processor of system 2, canbe configured with instructions to perform one or more of the steps ofmethod 700, and the tangible medium of the processor may embodyinstructions to perform one or more of the steps of method 700. In manyembodiments, the tangible medium comprises instructions of a computerreadable memory having instructions of a computer program to perform oneor more of the steps of method 700. Alternatively or in combination, thelogic array, such as the field programmable gate array as describedherein can be programmed to perform one or more of the steps of method700. In many embodiments, the processor comprises a plurality ofprocessors and may comprise a plurality of distributed processors.

FIG. 13 shows a corneal thickness profile map measured from a humansubject with an OCT system as described herein. The corneal thicknessprofile map can be fit with a spherical surface and the residual plottedagainst a sphere as shown. The data shows a deviation of over one micronacross the surface. Work in relation to embodiments suggests that an eyetreated to correct refractive error will have greater amounts of error.The corneal thickness map can be used to determine an axis of the eye asdescribed herein, for example an astigmatic axis of the eye when thepatient interface couples to the eye.

While preferred embodiments of the present disclosure have been shownand described herein, it will be obvious to those skilled in the artthat such embodiments are provided by way of example only. Numerousvariations, changes, and substitutions will be apparent to those skilledin the art without departing from the scope of the present disclosure.It should be understood that various alternatives to the embodiments ofthe present disclosure described herein may be employed withoutdeparting from the scope of the present invention. Therefore, the scopeof the present invention shall be defined solely by the scope of theappended claims and the equivalents thereof.

What is claimed is:
 1. A method comprising: using one or more of animaging device and a profile measurement device, generating one or moreof a first image and a first shape profile of an eye of a patient whenno patient interface is either in contact with the eye or located on anoptical path between the eye and the one or more of the imaging deviceand the profile measurement device; thereafter, placing a patientinterface in contact with the eye, wherein the patient interfaceincludes a suction ring which is in contact with the eye and anoptically transmissive element which is located on the optical pathbetween the eye and the one or more of the imaging device and theprofile measurement device when the patient interface is placed incontact with the eye; and generating one or more of a second image and asecond shape profile of the eye with the patient interface placed incontact with the eye; comparing the first image with the second image orcomparing the first shape profile with the second shape profile todetermine one or more of a position and an orientation of the eye whenthe patient interface is in contact with the eye.
 2. The method of claim1, wherein the step of generating one or more of a first image and afirst shape profile of the eye includes measuring the first shapeprofile of a cornea of the eye when the patient is supported with apatient support of a laser surgery system; and wherein the second imageis generated when the patient is supported with the patient support ofthe laser surgery system.
 3. The method of claim 2, further comprisingdetermining an axis of treatment of an astigmatism of the eye based onthe shape profile, the shape profile comprising one or more of akeratometry reading of the eye, a corneal topography of the eye, anoptical coherence tomography of the eye, a Placid disc topography of theeye, a reflection of a plurality of points from the cornea topography ofthe eye, a grid reflected from the cornea of the eye topography, aHartmann-Shack topography of the eye, a Scheimpflug image topography ofthe eye, a confocal tomography of the eye, or a low coherencereflectometry of the eye.
 4. The method of claim 2, further comprisingdetermining an axis of treatment of a plurality of arcuate incisionsbased on the shape profile, the plurality of arcuate incisions extendingalong an arc transverse to the axis of treatment.
 5. The method of claim4, further comprising displaying locations of the plurality of arcuateincisions on the second image of the eye after mapping the locations ofthe plurality of arcuate incisions from first locations of the firstimage to second locations of the second image, the second locationsbeing different from the first locations due to distortion of the eyewith the patient interface placed in contact with the eye, and whereinthe first image and the second image are generated with a camera of thelaser surgery system.
 6. The method of claim 5, further comprisingapplying a plurality of pulsed laser beams to locations of the eye totreat the eye by making the plurality of arcuate incisions.
 7. Themethod of claim 4, further comprising applying a plurality of pulsedlaser beams to locations of the eye to treat the eye by making theplurality of arcuate incisions.
 8. The method of claim 1, furthercomprising: modifying the first image to provide a distorted first imagebased on a correlation of the first image with the second image; andproviding the distorted first image on a display visible to a user. 9.The method of claim 8, wherein the modifying step includes the useradjusting one or more of a location or an angle of the first distortedimage on the display and wherein locations of a plurality of laser beampulses are adjusted in response to the location or the angle of thefirst distorted image on the display.
 10. The method of claim 9, furthercomprising applying the plurality of pulsed laser beams to locations ofthe eye to treat the eye.
 11. The method of claim 8, wherein themodifying step includes overlaying the distorted first image on thesecond image on the display to determine a position and an angle of theeye for treatment, and a processor determining the position and theangle of the distorted first image on the display in response to userinput to adjust locations of a plurality of laser beam pulses.
 12. Themethod of claim 11, further comprising applying the plurality of pulsedlaser beams to locations of the eye to treat the eye.
 13. The method ofclaim 1, further comprising: modifying the second image to provide acorrected second image based on a correlation of the second image withthe first image.
 14. The method of claim 1, wherein the patientinterface further includes one or more of a liquid or a viscoelasticmaterial disposed between a cornea of the eye and the opticallytransmissive element and wherein the one or more of the liquid or theviscoelastic is in contact with the cornea.
 15. The method of claim 1,wherein the first image comprises a first plurality of image structurescorresponding to a plurality of tissue structures of the eye and locatedat a first plurality of locations of the first image, and the secondimage comprises a second plurality of image structures corresponding tothe plurality of tissue structures of the eye and located at a secondplurality of locations of the second image, wherein the first pluralityof locations are different from the second plurality of locations due todistortion of the patient interface.
 16. The method of claim 1, whereinthe first image and the second image correspond to a coordinatereference of a laser treatment system, the method further comprisingmapping a plurality of locations of the first image from first locationsof the coordinate reference of the laser system to second locations ofthe coordinate reference of the laser system based on a correlation ofthe first image with the second image.
 17. The method of claim 1,wherein the first image and the second image correspond to a firstcoordinate reference of an ancillary diagnostic device and a secondcoordinate reference of a laser treatment system, respectively, themethod further comprising mapping a plurality of locations of the firstimage from first locations of the first coordinate reference to secondlocations of the second coordinate reference of the laser system basedon a correlation of the first image with the second image.
 18. Themethod of claim 1, wherein the first image of the eye and the secondimage of the eye comprise images of an iris of the eye and wherein oneor more structures of the first image and the second image correspond toone or more structures of the iris.
 19. The method of claim 1, furthercomprising applying a plurality of pulsed laser beams to locations ofthe eye to treat the eye, wherein the locations are determined inresponse to at least one of the first image, first shape profile, secondimage and second shape profile.